The acronym stands for Release to Manufacturing, and it means this latest release of Windows Server 2008 R2 is now blessed by engineering as ready for the manufacturing process. We're talking final code. Sun shining, birds singing, children dancing in the streets.
With evaluation software available for download in the first half of August and the full product available to customers with Software Assurance in the second half of August, RTM is more than just an engineering milestone. Occurring in lock-step with the release of the Windows 7 RTM, these two platforms are now ready for our partners to start testing and installing on their hardware. And that lock-step isn't a coincidence, it's a design goal.
More: http://blogs.technet.com/windowsserver/ ... 2-rtm.aspx