Today, Microsoft released RC builds for Windows 7 SP1 and Windows Server 2008 R2 SP1 without warning, and Windows 7 SP1 RC builds have been leaking onto the network for some time. This may be the reason why Microsoft had to bring forward the release of Windows 7 SP1 RC.
Windows 7 SP1 helps PCS take advantage of these server-based capabilities to provide a richer VDI experience for end users. In addition, SP1 has no new features specifically for Windows 7. All users running the legitimate Windows 7 RTM operating system can install SP1 for free.