Microsoft has released Windows 7 Service Pack 1 release candidate and Windows Server 2008 R2 Service Pack 1 for users running the final RTM version of the respective operating systems.
The build number of official Windows 7 SP1 Release candidate is 6.1.7601.17105.100929-1730 which is same as the one which was leaked a few days ago. The size of Windows 7 SP1 RC is hefty & weights around 514.7MB for x86 build & 865.4MB for x64 build.
Windows 7 and Windows Server 2008 R2 SP1 Release Candidate includes previous updates delivered over Windows Update as well as continuing incremental updates to the Windows 7 and Windows Server 2008 R2 platforms.
Windows 7 SP1 RC can be downloaded and installed if you have genuine Windows 7 & same will be available via windows updates once Microsoft releases final version to public which is expected to be announced at PDC 2010.
Download Windows 7 SP1 RC (Microsoft Download Center)