The GeoCommons site was officially launched on the 28th May at the Web 2.0 Conference in San Jose.
The aim of GeoCommons is "to make the world of detailed geospatial data on everything from crime statistics to meteorite strikes at your finger tips". This is amazingly cool.
The heatmap pictured here is "The hippest place to live in San Francisco". The brighter the heat spot, the greater the concentration of particular categories. In this case, SeaGor (who created the map) chose popular bars, low crime rate, density of tech workers, newer homes and female motorbikers as indicators of 'hip' and overlaid them accordingly. Interesting choice of categories.
See the blog as well.