SQL Server 2008 R2 service pack 1 contains all the cumulative update pack releases since RTM release. This means SP1 CTP consist the CU Package releases from 1 to 6, as CU7 has released on April 18th 2011. So before you test the SQL2008R2SP1 CTP, I would...
If you are interested to cast your vote & comment on getting Service Pack release for 2 important versions of SQL Server visit: SQL2005-sp4 & SQL2008-SP2 pages.