Is the new version of the service released on April 2011 replacing the previous January 2010 version?
No. The new version of the service is not completely backward compatible with the previous version, and it is running in parallel to the previous version. Existing customers will not be automatically migrated to the new version, and the previous version remains fully supported. For more information on the differences between the January 2010 release and the April 2011 release versions of the service, see the product documentation on MSDN. On MSDN, we will also provide guidance on how to migrate applications from the January 2010 version to the April 2011 version.