Since a few hours the Windows Server 2012 R2 and System Center 2012 R2 Preview bits are available on MSDN and TechNet. SO we can go ahead and download those files. It could be that relating to what access you have to these platforms you will see a few which are yet unavailable, but they will be available soon. In my case I could access all of them. B)
Also available are the preview of Windows Server 2012 R2 Essentials Preview, and the SQL 2014 CTP1 preview also seems to be here already if you are a die hard SQL fan.
SO now we can start playing around with some Windows and System Center R2 products and see what changed and what we like :p