Today, the last of the download links for the Microsoft Hyper-V Server 2008 R2, Windows Server 2008 R2 RC (Release Candidate) release, Windows 7 client and the Remote Server Administration Tools (RSAT) for Windows 7 RC have gone live.
Windows Server 2008 RC Download
If you have an MSDN or Technet subscription, the download has already been live for a few days.
As of today, you can also download directly. Follow this link and choose the "Download the RC now!" link at the top right of the page.
Microsoft Hyper-V Server 2008 RC Download
This is the standalone virtualization solution using the same Hyper-V technology present in Windows Server 2008 R2. It can be downloaded here.
Windows 7 RC Download
Follow this link to the TechNet Evaluation Center.
RSAT RC Download for Windows 7
The RSAT tools are packaged in KB958830 which you can obtain by following this link. Make sure you download the right architecture for your needs. Note that these require Windows 7 Client build 7100 to install successfully and do not install on Windows Vista.
Once you have installed the update, to enable Hyper-V Manager, in the Control Panel, open Programs and Features. From here, choose "Turn Windows features on or off" and navigate down through Remote Server Administration Tools/Role Administration Tools and ensure Hyper-V Tools is selected.
Note that if you have a full installation of Windows Server 2008 RC, the Hyper-V role management tools are available without enabling the Hyper-V role itself.