I just got an e-mail announcement from Arc2Earth (disclaimer: my company is a reseller) regarding some updates to version 3 that have come out since the ESRI UC. One of the updates that catches my attention is:
ArcGIS Server Tile Cache Format – You can now create or manage tile caches that can be used with ArcGIS Server. use Arc2Earth tile management tools (like the Change Detection Level) to dramatically reduce the time it takes to update tile caches