Building on my previous post on what citizens can contribute, one important additional point is that different skills are distributed differently.
In particular, IT skills belong to a small minority of the population, largely composed by cultivated young men.
Instead, specific knowledge is much more distributed, but still belong to an elite: not a technological elite, but a knowledge elite which is far more equitably distributed between gender and age. For instance, people writing on Wikipedia include many more women and elderly (as stated by Wikipedia Italy manager Frieda Brioschi at the recent Wikitalia event in Rome).
Finally, the other points are far more equally distributed among the population. Almost anyone can contribute through their trusted networks, experience of using public services, geographical coverage, many eyes and hands.