Friday Microsoft is supposed to officially release XPSP2 RC1 to the public. I jumped the gun and uploaded this latest SP2 today. Although a Beta, this service pack is in release candidate form and shouldn't see much in the way of change before the final is released sometime in Apr/May. If you just can't wait for the public release tomorrow, you can download SP2 by clicking on the 'About Windows' image above. Enjoy!
EDIT: For those using Windows 2003, uploaded the latest SP1.