From Microsoft via email:

Microsoft is officially announcing the release of Windows Server 2008 Hyper-V Release Candidate 1 (RC1), the hypervisor-based server virtualization technology. RC1 is a feature complete beta, and while there are no major build updates the announcement includes:

  • Support for additional guest operating systems. With RC1, Hyper-V now includes support Windows 2000 Server SP4 (1-way, emulated only) and Windows 2000 Advanced Server with Service Pack 4 (1-way, emulated only). Integrations components will not be available for these guest operating systems.
  • Simplified install for Windows Server 2008 ICs. With RC1, Hyper-V provides a simplified and consistent process to install the integration components for Windows Server 2008 guests.
  • Mouse integration support for Linux Integration components. RC1 of the integration components for supported Linux operating systems will now include mouse integration support. This will be released simultaneously with Hyper-V RC1. The integration components can be downloaded from http: //connect.microsoft.com

Hyper-V RC1 is an optional upgrade for customers and partners, providing the latest code for those who want to continue testing the technology within their infrastructure environment.  The current Beta of System Center Virtual Machine Manager 2008 (SCVMM) is not compatible with Hyper-V RC1. Customers who are simultaneously testing the recently-released SCVMM beta should continue evaluating it with Hyper-V RC0.  For customers who need to evaluate support for Windows Server 2000 as a Guest operating system, we recommend upgrading to RC1, but not manage those systems with VMM 2008 Beta. Because Hyper-V and SCVMM 2008 are on separate development schedules, an update for SCVMM Beta to enable support for Hyper-V RC1 will be made available at a later date. 

The RC1 Evaluation copy of the code will be made available here  for download by EOD on May 20th. For more information, please check out the STB News Bytes Blog  or Virtualization and Consolidation.