You can now evaluate Release Candidate 0 of Windows Server 2003 R2.

At http://www.microsoft.com/windowsserver2003/R2/default.mspx you'll find great info on R2 including

• Simplified Identity and Access Management: See how Windows Server 2003 R2 extends connectivity and control of identity management for internal and external collaboration.
• Get the Reviewers Guide: Delve into the Windows Server 2003 R2 Reviewers Guide and get started using Windows Server 2003 R2 in an evaluation setting. The Reviewers Guide also describes new features and explains how Windows Server 2003 R2 differs from earlier versions of Windows Server.
• Review Frequently Asked Questions: The Windows Server 2003 R2 FAQ provides helpful answers to common questions about the features and enhancements of Windows Server 2003 R2.
• Consult the Product Overview: Learn how Windows Server 2003 R2 makes it easier and more cost effective to extend connectivity and control to identities, locations, data, and applications throughout your organization.
• And, of course... Register to download the Release Candidate software