Anecdotally, it seems like they are moving out of there and moving in here. (Disclaimer: there's an alarming number of people here that are opposed to that. I'm not one of them.)
Thing to consider, though. There still isn't nearly the concentration of VCs (and thus networks) here as there are there. Depending on where you're at with your project/startup/company, that's got to be a sizable consideration when thinking about moving to/moving from the valley.
Also anecdotally, I moved to the Bay Area, my parents moved (back) to SoCal after 40 years in the Northwest grey. Plus, I have 4 dot-com era friends who have moved from the Seattle tech boom to the Bay Area tech boom, all in their late 20s/early 30s (so not just-out-of-college types), and I know a few others who are considering the same. And I don't know a soul from here who moved north, except for people who came down here for college and then returned home.
I guess it's like they say, "the plural of anecdote is not 'data'".