Today the Exchange Server 2007 Service Pack 3 Update Rollup 13 and the Exchange Server 2010 Service Pack 3 Update Rollup 5 were released
The URs can be downloaded here:
Update rollup 13 for Exchange Server 2007 Service Pack 3 (KB2917522)
Update rollup 5 for Exchange Server 2010, Service Pack 3 (KB2917508)
Unfortunately there is currently no exact description of which problems have been fixed, as soon as available I will link it here.