Originally slated to get their code on the 19th, volume licensing customers received the RTM build on the 12th–a full week early. The second half of August was still the target for the rest of the world, but we've burned the midnight oil this week and the result is that the Windows Server 2008 R2 RTM bits are available today! The eval bits are publicly available for download on ms.com.
Some quick details: The eval is good for 180 days, and once you install there's a 10-day grace period before you'll need to activate the software. Please note, however, that while product activation is required, the product key is actually built into the software so all you need to do is click "Activate Now."
TechNet and MSDN subscribers also get access to RTM in the form of full bits. This version requires you to enter a product key for activation, but that key is supplied when you download the code. Just log-in with your account credentials and start downloading. Enjoy the new server!