ESRI have just announced that their ArcGIS online map services have been migrated to the web tiling scheme used by Google Maps and Bing Maps. The original tiling scheme will remain live for at least six months but there will be no further data updates. Here is the announcement text:

In response to requests from many users, ArcGIS Online map services have been migrated to the Google Maps/Bing Maps tiling scheme in Web Mercator Auxiliary Sphere. This enables Web developers to more easily combine ArcGIS Online map services with other popular Web map services including those from Bing Maps, Google Maps, and other providers using the same Web map tiling scheme.

The existing services in the ArcGIS Online tiling scheme will remain available for at least the next six months and, depending on demand, may remain available longer. Although the services will remain available, the content will no longer be updated.

For more details, see Migrating map tiling schemes in the ArcGIS Online Help.

If you have questions, please post them to our forum.

Sincerely,
The ArcGIS Online Team