Windows 7 RTM was available on MSDN some days ago but Windows Server 2008 R2 wasn’t, although they RTM’d on the same day. Today it has been made available on MSDN (
not sure about TechNet ). So, if you’re an MSDN subscriber, go ahead and download it. All versions have been made available along with the keys.
Update: It’s available on TechNet as well. Thanks to Manan for the heads up!
Update 2: You can also download a free evaluation of Windows Server 2008 R2 from the TechNet Evaluation Center.