The Microsoft’s Partner Program site accidently mentions that Windows 7 RC would be available for public download on May 5th while MSDN and TechNet subscribers can download now. Currently the Windows 7 RC has not been available through the TechNet subscription yet, only the Microsoft OEM partners such as Dell, Siemens are taking part in the RC’s this period of test. This release candidate would be would very similar to the Windows 7 Final.
UPDATE : Microsoft has confirmed Windows 7 RC will be available for download on April 30th for MSDN and TechNet subscribers. Broader, public availability will begin on May 5th.