I know you're all sick of maps but fuck it, Forbes recently published this map showing where people moved across the country in 2008. Captured above is the dataset of where people moved into SF from (black lines) and where they left too (red lines). Not very surprising that the majority of departures were to the Greater NYC area, New Jersey, Portland, Seattle and Austin and people flocked to SF from SoCal, NYC, Chicago and Boston. Oddly enough, Massachusetts was the only state in which people moved to SF from every county, something even California couldn't claim. Multiple states didn't lose a single resident to SF, including a bunch of states that no one gives a shit about.
Anyways, click around the map too see how much wealth the city is losing to the Northeast.