Case-Shiller... bah humbug. Dataquest... better than a sharp stick in the eye, but not by much. Talking heads on CNBC... please stop talking. So WHO can you listen to when trying to figure out what is going on in the LOCAL San Francisco real estate market? Well, the two best things to do are go to open houses and scrutinize the market for months, and you'll get to know it better than anyone. The 2nd is to turn to someone who does that for a living... a hard working Realtor. But if you just want data... a quick place to check in on the market once per month... Trulia's "heat map" with (and this is critically important) it's ZIP CODE box checked.
Zip codes aren't even as "local" as I'd prefer, but the map will show you the border outlines for each zip code, and then you can see the "year over year" or "y-o-y" difference in "Average Selling Price" and "Median Selling Price". Median is probably best - half sold for more, half sold for less, than the median. "Average" can be skewed by just one or two really high priced (or low) sales.
You can then sort by zip code, or by highest appreciation, or highest depreciation. A quick guide are the color codes - which change as you sort in different ways. And to see the what area is what zip code, just hover your mouse over the map.
The most unfortunate thing about Trulia's heat map is that I'm writing this at the end of December, and they only have July through September data. It shows zip codes 94118 (Laurel Village, Lake and Inner Richmond) as being up 9.9% year over year (surprised????) but as a San Francisco Realtor with "feet on the street" I know the market lost that entire 10% after the financial crisis became mainstream news.
But Case-SCHMiller is old data too and does not have San Francisco City only data... so I find it to be totally worthless, and Dataquest does do San Francisco only, but does not get any more local than that. And as the old adage says, real estate is local, especially San Francisco real estate.