Microsoft has made available the release candidate for Virtual Server 2005 R2 SP1.  It can be downloaded here.  If you have not already signed up for the beta program, go here. 

This release of Virtual Server 2005 R2 SP1 includes the following features:

• Support for hardware-assisted virtualization
• Support for greater than 64 virtual machines on x64-based hosts
• VHD Mount command-line tool and APIs
• Interoperability with Volume Shadow Copy Service
• Support for additional Guest and Host Operating Systems
• Service Publication using Active Directory Service Connection Points
• Host clustering whitepaper
• Virtual SCSI fix for Linux guests
• Larger default size for dynamically expanding virtual hard disks
• VMRC ActiveX control and Internet Explorer Security Zones
• IVMGuestOS::Get_OSName property returns more operating system information

Thanks to Richard Cardona for news!