Windows 7 SP1 and Windows Server 2008 R2 SP1 released
While Windows 7 SP1 doesn't bring any standout features for the consumer, Windows Server 2008 R2 SP1 (what a name!) does include some important back-end improvements to both performance and security. Highlights include the addition of Dynamic Memory, which enables a higher density of virtual machines to be set up; plus RemoteFx, which adds greater graphical power for thin-clients giving them more of the full Windows experience.
Head on over to Microsoft for the full and sordid details, while you can either hit Windows Update for a smaller, more tailored download for your system, or download the full thing from the Microsoft Download Center.