Thanks to the 2008 stimulus act, the federal government has been insuring about six mortgages a week in San Francisco -- compared to none for all of 2007. Traditionally, loans underwritten by the Federal Housing Administration are for the poors ("in low-cost states like Texas and Michigan"), but the bar's been raised, allowing middle- and upper-income buyers into the game.
Profiled in the New York Times: three friends who dropped $33K in order to buy a Hayes Valley building. The idea? "We're banking on real estate. Everyone expects prices to keep going up."