|The divine comedy|
Organized complexity is, simply put, things that look designed. (They don't have to be designed.) This is, by definition, a subjective term (since things look different to different people) and therefore scientifically useless.
How can things just up and organize themselves?
At the molecular/cellular level, interactions are governed by Brownian motion (a phenomenon unfamiliar at the macro level) and may better be thought of as complex adaptive systems rather than Newtonian balls.
It is also the case, as Steven Johnson notes in his book, Emergence, that many apparently random, chaotic and infinitely complex collectives do organize themselves into meaningful patterns — "organized complexity". Phenomena cited are ant colonies, cities, and "learning" software that creates at least a mime of intelligence.
The basic force at work is that of guiding principles, laws, instructions — that are repeated — and these repeated instructions, such as one might find in DNA, for instance, manifest themselves in patterns, and then patterns into form. So from ideas, laws, or principles and form of life materializes. And this comes not from an authorized signal-giver, but rather "from below", integral to the "swarm" itself.