Paul Buchheit: Looking for a co-founder? Try attending the REAL startup school.
paulbuchheit.blogspot.com
paulbuchheit.blogspot.com
I'm going to meet as many people as I can at startup school, but will probably need to go further than that. I've had a startup before, and learned alot from it, but I wasn't in the "startup community" at all. As far as working for a startup, many founders won't want you networking for your own stuff, they want you performing tasks for their function. So it has to be done either covertly, or in the open with the founders blessing.
Also, judging by the people I met at the startup school - few have an actual business with customers and such, except for YCombinator founders (in most cases, not even them ;-)). If they did, they'd probably be attending to the business instead. Many, however, had an idea for a business or a very-early-stage business (some product development, possibly a small prototype in front of potential customers).