My point is this--I suspect that relocating yourself to San Francisco with an idea but without hacker friends that already live there (or ones that plan to) isn't going to get you very far. It would seem that everyone in the valley is very focused on their idea and bringing it to fruition and doesn't have any intention of letting you in on their venture just because you happen to also now live in the Bay Area.
Maybe I'm wrong, though; maybe there is a place where post-college hackers in the bay (PCHITB) freely mingle such that newcomers sans partners/friends can enter into their startup, which is otherwise a closed (intentionally so) society; maybe this is a part of the essence of things like Y-Combinator dinners, super happy dev house, etc. Just thinking outloud at this point. :-)
I'm not convinced that living in the Bay Area (or a similar hotbed) is essential. However, I do agree with what I believe is the underlying premise--that living in an area of concentrated geekdom will expose you to other geeks in a good way. But that can occur in college, or at a great company, and many of those exist outside of the Bay Area, albeit with much less frequency . . . but to say that you couldn't find a great hacker in Chicago or New York or Houston if you hung out at the right schools and businesses is a little strong. Then again, if it's a numbers game, then by all means go to San Fran. But in some sense it reminds me of how many people hang out in Palm Beach hoping to fall in love with someone that just happens to be a millionaire. My suspicion is that geek cliques do form, and they often form in college. That to me is the bigger point than saying 'if you want to start a startup, you should put a flower in your hair and . . .'.