If you are going for upgrading your server to Exchange 2010 SP2 and RU1 you may want to read some of the important notes included into release notes here.
From my experience the execution policy is something you MUST pay attention to it, also schedule more then twice time you would do for these upgrades as they will take long time (-:
One of the things to watch out is Execution policy, and its side effects , even though the release notes talk about it, some of the admins who have missed to pay attention to this ended up loosing entire exchange server and did have to go for recovery.
To verify the execution policies before you begin the installation, run the following Windows PowerShell cmdlet:
The output should resemble the following:
Oz Casey, Dedeal ( MVP north America)
MCITP (EMA), MCITP (SA)
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server +