Microsoft on Tuesday made available yet another in a seemingly endless stream of interim product updates with the release of Windows Server 2003 Release Candidate Zero (RC0).

The software is a preview of technology that will be included in Release Candidate 2 (R2) of the server operating system, which is expected to be available before the end of the year, according to Microsoft
http://www.infoworld.com/article/05/...sserver_1.html
Infor World :: August 30, 2005

Or straight from the horse's mouth :

http://www.microsoft.com/windowsserv...2/default.mspx