UR5 for Exchange 2010 SP1 is now released. It contains several bug fixes. Here is the description Exchange 2010 SP1 UR5 - 2582113.
Problem with PDF attachment from MAC clients should finally be resolved. Also the error message "There are no items to show in this view." in Outlook 2010 is resolved.
Here is the download link
The usual warning for customer running forefront security for Exchange is to disable forefront with "fscutility /disable" before applying rollup and afterwards enabled forefront again with "fscutility /enable"
How to Apply Exchange Service Packs and Rollups to a Computer that is Running FSE