Facebook seems to be constantly in trouble over "privacy" but what does this even mean? Is it just a scare or a scam, or is it really sinister?
It's easy enough to skip to just the bottom line here; if you don't want something made public, don't post it to a public place. I fail to see how the argument gets more complicated, but lets press on anyway. For instance, you wouldn't scrawl your bank details onto several pieces of paper and scatter them around the place. You wouldn't publically list your phone number without accepting that perhaps, it might get taken up and put on a list for telemarketing. You wouldn't put a giant sign on your house saying that you'd be away on holiday for two weeks and the keys are left in the plant pot by the garage door. Privacy is important, but the concept only applies to people trying to actively crack what you choose to keep private - if you close your bedroom door, you don't expect the prying eyes of the press or the state to come in and dictate what you can and cannot do with your wife and a large tub of lube. Similarly, you trust your bank account number, debit card number, PIN (your personal identification PIN number, no less) to a bank and anyone trying to access it illegitimately is breaking your privacy (and committing a major crime too).
In short, you have stuff you choose to make public, and stuff you choose to keep private. Private can only, pretty much by definition mean "information only entrusted to yourself". I know the thoughts that go on in my head - all that really fucked up stuff that everyone thinks of and pretends not to think of, you know - and people can't really break that privacy. When you go beyond that, you're relying on "privacy" meaning "entrusted to yourself and only people you want to know it". Okay, that's a workable definition; but it relies on trust. Some of this trust is legally binding, like your bank details, other trust is just taken on friendship - like the time you revealed one of those fucked up thoughts to a close friend.
 Online vs offline
The online world possesses some similarities and some differences to the "real" world - although the boundaries between the two are blurring every day. On the one hand, the real world intrudes into your life far more than any social networking tool can. For example, you walk into a shop and - SHOCK! HORROR! - people can see your face. Hell, they can see where you shop! They can see your tastes in music by watching you browse the "Country & Western" section of HMV and the shop assistant will even see which CD you bought. Damn, quite invasive this "real life" thing, isn't it? Do we deal with such heartless intrusions into our lives by curling up in horror, no, we react in a pragmatic way. We realise that people really aren't that interested - afterall, we aren't interested in them. We realise that we are nameless faces in a crowd, unrecognised, anonymous - we could be anyone, really.
Into this mix we throw the online world. The internet is a great thing, don't get me wrong, it has a great power for good and many people the world over can be enriched by its existence; but logging on to a proprietry piece of social networking software is not - I repeat not - a human right. It is no more a human right than owning a Ferrari, or a gun, or a pet, or perhaps even a phone. Therefore we must accept the costs of our actions and ignorance of the system is not an excuse. The online world, compared to the real world gives us more control over our privacy. We have to go outside and show our faces, we don't have to go online and poster it everywhere. We have to give our contact details to people who need to contact them, we don't have to post them on a networking profile for all to see. I'm currently sat - while writing this - in a public computer room on a University campus. People could look over my shoulder and read this any time. Indeed, it'd be interesting for them to look over my shoulder and read as I'm typing this sentence about people looking over my shoulder and reading this sentence about them. I accept this. I don't need to be here, I could dick off elsewhere, but decided to come here to pass the time. Similarly, I accept people are watching and I'm not going to be downloading hardcore pornography or instructions for manufacturing dirty bombs any time soon.
In short; I know the environment, and I adapt the information I release accordingly.
My take home message is that "ignorance is not an excuse". Tom Scott's "Evil" site shows this better than anything else, I think. It scans Facebook's public groups - these are groups with content explicitly stated to be available to the public, those with or without a Facebook account - that are on the theme of "hey guys, I lost my numbers!" and then picks them out to display them. Nothing that can't already be done, just automated. Remember, these people have explicitly chosen to write their contact details onto a public forum. If they were duped into thinking it was safe because of Facebook's friendly and intimate setting, that is their problem and their own fault. We don't have much sympathy for victims of 419 scams because they are victims of their own ignorance and stupidity. We don't have sympathy for someone who logs into their email and then saves it on a public computer. Similarly, if someone would like to post their full address online, it is their choice and theirs alone.
It'd be easy to bring up examples where privacy agreements have been violated, but this is still a case - as disgusting as such breaches of trust are - of "so what?". The first incarnation of MySpace famously sold all the data it collected after it went bust (this was in the years before "social networking" became the big thing) and I don't find my heart bleeding for people who posted their data online in a place where it can't be removed. If someone releases their information, they are operating on trust. A corporation violating their own privacy guidelines is no different to a close friend breaching the confidence of a secret. An individual who releases the information takes it on trust, and they also accept the risk that this trust can be broken.
 Follow the money
Let's, for a moment, consider the claim that Facebook is selling your data to corporations. In one sense, it's true, but what is it really? The implication seems to suggest an image of Mark Zuckerberg standing in a dark underground carpark, holding a packet of secret documents and waiting for a shading figure from Big Business to come along. The two exchange packs and Zuckerberg walks away with a big wad of cash and Big Business walks away with... well, what? The knowledge that Paula Nancy Millstone Jennings likes cats and her favourite quote is "live everyday like it's your last"? How incredibly useful for Big Business. What is actually happening is that Facebook takes your data and compiles a set of demographics which it then uses in its targeted advertising program. A business wants to sell a soft drink, it simply stipulates its ads appear for people who already "like" Coke or Fanta. It's actually quite open, and providing you're willing to pay for the adverts, anyone can do it and choose which demographics to target. At no point do the "Corporations" get any personal data fed to them. That's actually what happens. Nothing more. Somehow, the image conjured up of Facebook selling your oh-so-private data to Big Business isn't terribly accurate, and the reality is hardly impressive.
Awareness is the key to overcoming this obvious problem of privacy breaches, but panicky actions that throw the blame squarely on a corporation or website are not the solution. Yes, these places could make controling privacy easier (personally, I like being able to power user my way through FB's countless privacy settings, hiding my contact details from all but a select group of needed people, the micromanagement options are incredible). But this doesn't solve the basic problem; no matter what you do, you can't stop people being idiots. You can create a "privacy aware" network, you can make your privacy agreement water-tight and simple to enforce but the problem of privacy violation is systemic within our own complacency, not within the websites that we use.
In conclusion, for those interested, here is my address and phone number
I wanted to keep this focused on the idea of social networking and contact information. Stuff like Google saving websearches, I believe, is a different kettle of fish - although a similar breed of fish in a similar make of kettle. What data they do and do not collect (but most imporantly, what data is eventually seen by human eyes and used rather than held within the algorithms) is an important issue, and I don't mean to completely side-step it, just move it to a different discussion for another time.