My firm, Pacific Union, has a much more interesting take on San Francisco's real estate market that the two articles in my earlier post.
Discussing the "rate of demand" vs home supply for San Francisco single family homes.
Supply - or homes available for sale in San Francisco have only increased by 0.1% per year since 1998 from just shy of 63,000 homes to just above 63,000. "Rate of demand" is the percentage of all single family homes that sell in a given year. San Francisco's average rate of demand has been 4.7%. At that pace it would take 21.3 years for the entire inventory of homes to change hands.
When demand is above average prices tend to climb, when below, they tend to drop. More details and Pacific Union's take on the 2010 San Francisco market can be found here, and the chart is below: