There is an excellent article at STL Today about neighborhood organizations. Refreshing to see are the positive comments from readers. A lot of the discussion is on the interaction on social media versus neighbors showing up in face to face meetings.
No matter how busy you are, there's no replacing face to face meetings. Twitter, facebook, myspace etc do not take the place of showing up in person, especially when you consider that many people do not use these services at all.
Alley cleanups, neighborhood watch, community gardens, block parties etc all happened long before the advent of social media. Read the comments at STL Today's site. It's clear that among the strengths of urban neighborhoods are the active neighborhood organizations serving our communities.