Late last week ESRI announced that its ArcGIS Online services will be migrating to the Mercator-based tiling scheme used by Google Maps and Bing Maps by the end of the year. Previously these services have used the WGS 1984 geographic coordinate system with a 512 x 512 pixel size. Google Maps and Bing use a modified Mercator projection with a 256 x 256 tiles size. The differences between ArcGIS Online and the popular Google Maps and Bing tiling schemes caused problems for many organizations. According to ESRI,
Some organizations struggle with choosing either the ArcGIS Online tiling scheme to match their ESRI software stack, or the Google / Bing tiling scheme to match a better-known standard. With a unified tiling scheme for the three services, the decision gets a lot easier.
The post goes on to discuss the advantages and challenges of switching to the new tiling scheme and also discusses a workflow for caching your maps in the new scheme.