We rent a coworking space in SF, and it was very beneficial. A bunch of startups share the same space, and we are constantly exchanging information, ideas, contacts, etc... I think that's the most important thing about coworking: It's not much about the space itself, but about the community formed around the shared space.
The page contains a list of cities where there are co-working arrangements or groups willing to arrange something. Select your city and see what's there. Or, you can start something yourself and add your city (it's a wiki). They also have a Google group to communicate and a blog. I think they're doing a great job promoting the concept.
