Price Per Square Foot Heat Map

I found this heat map of price per square foot in San Francisco that Zillow posted awhile back. It was a realy intriguing map, but a little low on resolution to gather any block speck specific information. I blew the image up, made it transparent and laid it over a more detailed map of San Francisco to the best of my ability. A little intriguing: price per square foot along 24th or Valencia in the Mission was some of the lowest in the city. Really? Likely, this data was aggregated over some time range that goes far back. Not sure. But it just spawns the idea of how awesome this would be: Imagine looking at a movie of the price per square foot heat map in the city, watching some regions / neighborhoods value increase while others descend. Also would be interesting to see a heat map of very recent (last month or year) and compare with the longer term average. Also volume and inventory. These would all be indicators of trends in san franciscan's perception of value for these geographical regions.