Seem's that NEOWIN.net had managed to get their hands on the internal schedule for the release of Windows XP SP3 :
- April 14, 2008: Support is available for the release version of Service Pack 3 for Windows XP
- April 21, 2008: Original Equipment Manufacturers, Volume License, Connect, and MSDN and TechNet subscribers
- April 29, 2008: Microsoft Update, Windows Update, Download Center
- June 10, 2008: Automatic Updates
It looks like the real thing (I think we can trust NEOWIN), the news was also publish by bink.nu