Quoting from Winbeta:
Microsoft has notified participents enrolled in the Systems Management Server 2003 Open Beta program that a build of Service Pack 1 is now available. Previously only the SP1 SDK had been available.
According to Microsoft SP1 includes a series of enhancements to tighten security, increase reliability and improve scalability of SMS.
SP1 also broadens the supported configurations to include Workgroups along with support for both Virtual Server 2005 and Virtual PC. The final version of SP1, due in June, will also include advanced client support for systems with 64-bit processors.