Microsoft is continuing its commitment to quality and released RC build of Service Pack 1 for Windows 7 and Windows Server 2008 R2 to Microsoft Partners and Selected Testers (It is not public release). The RC Build is 7601.17105.100929-1730 that indicates the build was compiled on September 29th 2010.
Microsoft offers more localized versions of Windows 7 SP1 to testers and rolled out it with Wave 0 and Wave 1 languages. The upgrade is being delivered as Standalone package and via Windows Update only.
The impact of SP1 on the Windows 7 client operating system is considered to be minimal and addresses minor usability issues in specific scenarios. Microsoft recommends that organizations do not need to wait for SP1 to begin receiving the value of Windows 7 today. Service Pack 1 for Windows 7 and Windows Server 2008 R2 includes previously released updates and a number of powerful virtualization features for Windows Server 2008 R2 i.e. Dynamic Memory and Microsoft RemoteFX.
Dynamic Memory Windows Server 2008 R2 Hyper-V introduces a new feature, called Dynamic Memory, in the Windows 7 SP1 and Windows Server 2008 R2 SP1 Beta releases. It allows customers to achieve increased density when they’re consolidating physical servers into a virtual realm, providing them with predictable performance and linear scalability. With Dynamic Memory, IT administrators are able to pool available memory on a physical host and then dynamically dole that memory out to virtual machines running on the host, based on current workload needs.
Microsoft RemoteFX A key feature of Remote Desktop Services (RDS) lets IT administrators deliver a rich graphics experience to end-users through virtualized desktops. Using new protocol enhancements between Windows Server 2008 R2 and Windows 7, end users can now access virtual machines on a wide variety of target devices and still get a rich graphics experience with server-side graphics processing.
A nasty rumors in wild that some post-Beta or RC Escrow builds have been leaked on torrents. It is recommended to avoid such leaked builds, it may contain virus and compromise Window security and stability.
As mentioned above, its not available for general public. So if you want to tryout Windows 7 SP1, a public beta build of Windows 7 SP1 were already made available.