From the KB Article ID: 981355

“Cumulative Update 1 for Microsoft SQL Server 2008 R2 RTM contains only hotfixes that were released in Cumulative Update 5, 6, and 7 for SQL Server 2008 Service Pack 1 (SP1). Cumulative Update 1 for SQL 2008 R2 RTM is only intended as a post-RTM rollup for Cumulative Update 5-7 for the release version of SQL Server 2008 SP1 customers who plan to upgrade to SQL Server 2008 R2 and still keep the hotfixes from Cumulative Update 5-7 for the release version of SQL Server 2008 SP1. No new hotfixes have been included in this cumulative update.”

Get the info and listing of fixes here