Microsoft has published release candidates of Service Pack 1 (SP1) for Windows 7 and Windows Server 2008 R2, you can grab it over here. These service packs are primarily aimed at fixing bugs, as Brandon LeBlanc blogs, these updates contain very little new features:
As previously announced, the only new features added to the SP1 are the Windows Server 2008 R2-related virtualization technologies, Dynamic Memory and RemoteFX – please see the Windows Server Division Weblog for more details. These features will help customers who choose to deploy Windows through Virtual Desktop Infrastructure (VDI) by enabling a more scalable and rich user experience.
While Windows 7 SP1 will enable PCs to take advantage of these server-based features to provide a more scalable and richer VDI experience for end users, there are no additional new features specific to Windows 7.