Exchange 2010 Service Pack 1 Update Rollup 3 was the fix for the memory leak found in Exchange 2010 SP1. You can read more about that on one of my previous article’s here. Unfortunatly that fix was removed on the 14th March 2010 due to the fact that the fix intrduced another problem with Blackberry Enterprise Server, more commonly known as BES.
RU3 version 14.01.289.007 has now been released and you can find a full description of the update on the following knowledge base article KB2529939.
Microsoft are strongly urging that everyone should apply this update as soon as possiable and dissregard any previous versions which you may have.