I don't see a bubble as of yet. What's driving the prices up in the Bay area is the tech jobs, SF is only 49 square miles, at the tip of a peninsula so there is no room to grow thus as long as tech and related industries IE angel & venture capital, asset management etc., keeps creating jobs and SF's housing prices will go up.
Here's a silly question... But how in the world do cops, teachers, etc eek out an existence there? Let alone the min wage employees. Must be a long ass daily commute.
Simple answer is they don't, they live 30-60 miles away in Novato, Rohnert Park etc., though policemen and firefighters with over time do make over $100k which is nothing in SF eg http://www.mercurynews.com/2012/09/08/contra-costa-grapples-with-high-firefighter-payouts/ I see a lot of restaurant employees, bohemians living 5, 10 to an apartment. In the city ( and Bay area) you have a lot of Asians ( majority) and most of them live in an extended family environment.
DM.... if I was out there... I'd be buying everything I could afford in the middle price range out in Novato, Rohnert Park and flipping them like pancakes. Hot markets like you have going on right now out there are a 1000 times more profitable than trading. If you have the $'s, its low hanging fruit. Being nimble is key. As long as no end is in sight... buy above the ask.... and sell. Just like stocks in a super-bull market.
Pre-2008 almost every other person were flipping homes, I haven't come across that many flippers this time around.
Its tougher to get a mortgage now. That's why I said "if you have cash". Its low hanging fruit in that market right now.
While I am sure there are investors still flipping, we are now past the point of easy money; markets are now efficient and its up-to the pros to flip. You don't want to be in an episode of "DEED".