From The Inq.THE WINDOWS XP SP2 RC2 is delayed, linked to a fault with NX CPU execution protection. Web site Neowin has confirmed that RC2 isn't likely to be released to beta testers until next week.
2138 is the latest internal compile, but is yet to be slapped with the RC2 tag. This suggests that the 2139/2140 will probably be the RC2 build and is likely to ship to testers in a weeks time at most. At first, Microsoft were pressing for a June release date for the service pack, but bugs, delays and the typical development downsides got to them, and have delayed the release until July.
The Longhorn project has pretty much come to a halt, since the build team are focusing on getting the XP SP2 up and running as quickly as possible.
Original Neowin Article