Microsoft has released SQL Server 2008 R2 SP2 CU9, which is Build 10.50.4295. This CU has eighteen hotfixes in the public fix list. Some of the more important ones are listed below:

FIX: Poor performance when SQL Server 2008 or SQL Server 2008 R2 requires memory from a local node in a NUMA environment

FIX: Nonclustered index corruption may occur when you run a complex UPDATE statement together with a NOLOCK hint against a table in SQL Server 2008 or in SQL Server 2008 R2

FIX: It takes longer than expected to create a filtered statistic after you create a clustered index on a partitioned table in SQL Server 2008 R2

If you are running SQL Server 2008 R2, you need to be on the SP2 branch, since the SP1 branch was retired earlier this year. If you are on SQL Server 2008 R2 SP2, I think you should be planning on getting on the latest CU9 as soon as it makes sense. That does not mean you install it in Production the day it is released, but rather, you have a set procedure and test plan that you follow (just as you would for any other type of change), that you actually execute on a regular basis.

Being proactive with important updates as part of a regular, well planned and tested maintenance procedure will reduce the amount of problems you have with your system over the long term.