The earlier reports on Vista SP1 were right on mark as Microsoft has announced their plans to release the final version of Vista SP1 in the first quarter of 2008. The Redmond giant has already delivered Vista SP1 to a group of approximately 12,000 beta testers. If you are thinking that the Service Pack 1 will at last provide major interface improvement or some cool new features then you're in for a disappointment as the new version focuses on "improving performance, reliability and application compatibility." The most unexpected change comes in Windows search function as integrating third-party programs (such as Google Desktop Search) is much easier now. It extends support for emerging hardwares such as the exFAT file system, Direct3D 10.1, and Secure Digital (SD) Advanced Direct Memory Access (DMA).
Microsoft also claims that the SP1 edition will speed up copying and extracting files, make PCs return more quickly from Hibernate and Resume modes, and improve laptop battery life by reducing CPU utilization. It'll also beef up computer security and fix problems that Windows Vista has encountered with newer graphics cards.
Source
http://www.pclaunches.com/software/first_thought_on_windows_vista_sp1.php