As of 7th of May, you can download the Windows 7 Release Candidate. Yes, the RC is now available and features several changes and improvements since the beta release, including improved boot performance, FAT32 support, and User Account Control (UAC) design changes. To assist in your evaluation, here are some key resources:
Download your free copy from:
Windows 7 Release Candidate Customer Preview Program
Remember, it's license will expire on 1st of June 2010
P.S. Coinciding with the Windows 7 RC, you can now
download the Windows Server 2008 R2 Release Candidate.