Last night Microsoft released two new cumulative updates for SQL Server 2008 R2:
Cumulative Update 5 for SQL Server 2008 R2 SP1
My recommendation: You should test and plan for this update if SELECT @@VERSION is between 10.50.2500 and 10.50.2805.
Cumulative Update 12 for SQL Server 2008 R2 (RTM)
My recommendation: Consider applying if SELECT @@VERSION is between 10.50.1600 and 10.50.1809, you are affected by any of the issues highlighted in the KB article, and you are avoiding Service Pack 1 intentionally (otherwise you should install SP1 and CU5 for SP1).
My usual disclaimer: these updates are NOT for SQL Server 2008. Only apply to systems where @@VERSION returns 10.50.xxxx.