Per CommunityWiki:"An organizational structure in which individuals choose roles and tasks for themselves and execute them. Responsibilities attach to people who do the work, rather than elected or selected officials." Put another way, it is the act of transforming the phrase "somebody should really do X" into "I should really do X".
Noisebridge has a Much better page on this at this time.
- Somebody should list some well-executed do-ocratic tasks around i3 here...