i've done some change mapping on the dutch tile server [1], blue is new/change, red is deleted it is using the mapnik db and does a daily comparison on the planet_osm_line table, just some simple sql's and every week i take a clean copy to reset the changes [1] http://tile.openstreetmap.nl/~rubke/change/?zoom=8&lat=51.90388&lon=5.74209&layers=0BFT