A while back in New Additions and Promotions in PostGIS Development Team, I mentioned that the new addition to our team Bborie Park was working on image output functions for raster support, among other things. His last addition was ST_AsRaster which allows a PostGIS geometry to cross the line to the raster world, all in the database. This new addition almost completes the basic cycle of making PostGIS not only a spatial analytical tool, but also a rendering engine.
There is still much room for improvement, e.g. intersection of 2 rasters, faster response, etc, but I can see all the lights flickering and the connections coming together like a self-orchestrating organism. From chaos comes order.