Robert Stein at ActiveWin has the email sent to beta testers:
Windows Serviceability is pleased to announce the release of the Beta 1 release of Service Pack 2 for Windows Server 2003 and Windows XP x64 Professional customers.
Service Pack 2 is a conventional service pack consisting of all security updates, all individual hotfixes released to customers and fixes to reduce top customer support issues as well as increase reliability, robustness, and security. Service Pack 2 is the first Service Pack for Windows XP x64 Professional SKU. Service Pack 2 also updates customers running Windows Server 2003 RTM, SP1 and/or R2 releases.