For Windows Server 2008 R2, SP1 will be introducing two new desktop virtualization features: Microsoft RemoteFX and Dynamic Memory. These features are designed to meet the increasing needs of our customers as they utilize virtualization in their environments with Windows Server 2008 R2. You can read more about RemoteFX and Dynamic Memory on the http://blogs.technet.com/windowsserver/
For Windows 7, SP1 includes only minor updates, among which are previous updates that are already delivered through Windows Update. SP1 for Windows 7 will, however, deliver an updated Remote Desktop client that takes advantage of RemoteFX introduced in the server-side with SP1 for Windows Server 2008 R2.