Microsoft released the third service pack for Windows XP to manufacturing on Monday, and the update isn't scheduled to be distributed to the public until April 29. However, with SP3 already available to MSDN and TechNet subscribers, the installer has leaked out into the wild.
Leaked service packs tend to be the domain of pirate networks, but we see that download sites Softpedia and MajorGeeks are offering SP3. The service pack is even available on FileShack, as well. The file on all three sites appears to be the same, bearing the name "WindowsXP-KB936929-SP3-x86-ENU.exe" and a file size of 316MB.
Naturally, we'd recommend that users who don't want to take risks wait until April 29 for Microsoft to publicly release XP SP3 through Windows Update. (Thanks to InfoAddict for the heads-up.)