YES, RC0 of the Microsoft virtualization solution Hyper-V is available for download. John Howard has an excellent and extensive blog post about the details.
Please pay close attention to his post and read 'til the end before you install the bits! It is important to follow the steps outlines in John's post, that's why I won't share the download links here.
More details also on the Windows Server Division weblog: Hyper-V: It’s all coming together
Read the complete post at http://blogs.msdn.com/volkerw/archive/2008/03/19/hyper-v-release-candidate-available.aspx
Mar 19 2008, 11:01 AM