Yesterday we announced that Windows 7 and Windows Server 2008 R2 have been released to manufacturing. Does this mean that you can start downloading it today? No but if you are a TechNet subscriber you will be able to download the English version on August 6th and the remaining languages Oct 1st.
Have a look at the Windows Blog to see what the different timelines for download are.
Additionally the Virtualization team blogged about the new capabilities of Hyper-V into Windows Server 2008 R2