Hi, Michael--Funny you should ask, I was just finalizing my Inside SF Real Estate blog post for tomorrow on that subject. The conforming loan amount is currently $625,500, but it will increase soon to $729,750.
If you're considering purchasing a home in San Francisco, you'd be looking at needing a 10% down payment, which would put your purchase price max at around $695,000. There are FHA loans available that require less down payment, but your purchase price would shift accordingly.
In case you're wondering what's available for up to $695,000--assuming you're working with a 10% down payment--here is the scoop: There are 210 single-family houses on the market, ranging in price from $179,000 for a 625-square foot, one-bedroom short sale house that's tenant occupied in Bayview, to a three-bedroom home in Bernal Heights on College Terrace. In addition to Bernal and Bayview, neighborhood selections include Merced Heights, Ingleside, Outer Sunset, and Sunnyside.
There are 493 condos available, but it's important to have your lender or mortgage broker review a particular building prior to even considering making an offer. Lenders are hesitant to lend on condo buildings, so there are further limitations to what you may be able to purchase.
I'd recommend considering properties priced as high as $725,000-$750,000, as your chances of negotiating for what you can afford increase the longer the property sits on the market--presuming you have a motivated seller on hand.
May be more info than you need, but I thought you may be interested in the full scope of things in the city.