CTP5 is available today!
http://www.microsoft.com/downloads/details.aspx?FamilyId=3BF4C5CA-B905-4EBC-8901-1D4C1D1DA884
Jamie has already blogged about some of the new goodies in CTP5, which include Intellisense for Management Studio. Also new in this release is the FileStream feature, which is something I've been working with recently. I plan to have more to say about FileStream soon.