At the FOSS4G conference I was charmed to see a bunch of cross project hacking ... in the form of a meeting about "Tiling".
The result of this meeting is just now been made available:
WMS_Tiling_Client_Recommendation
The origional that I linked to earlier is here: Tile Map Service Specification (thanks to Schyler for the correction).
While this is an exciting concept, the excitement has spread...
