
Median sale price is a poor way to measure price movements for a diverse market like the Bay Area. It is sensitive, not only to price movements, but to changes in the mix of homes as well. July's results are a case in point. The best-performing county in the Bay Area was Santa Clara, where the median sale price rose by 10% compared to June. Yet the median sale price for the entire Bay Area rose by 12%. The explanation for this odd result is that sales volumes fell in some of the less expensive counties, and rose in some of the more expensive counties. The Case Shiller indexes were specifically designed to eliminate this problem.
Having said that, I'm usually too impatient to wait an extra month for the Case Shiller numbers. I'm mainly interested in county-level numbers anyway. Here's a chart of median sale prices for San Francisco County.

By the way, the commonly quoted Case Shiller indexes are for single family homes only. Focusing on that statistic can cause its own problems if you're interested in a market like San Francisco, where condos comprise such a large fraction of the housing stock.