SQL Server 2008 July CTP
Hot off the presses. You can download it and get more details at https://connect.microsoft.com/SQLServer/content/content.aspx?ContentID=5395. The SQL team has put together a really helpful page that shows you a diagram of what's new:
When you click on a box in each of the pillars, you will get a more detailed explanation of what's new.
Learn more about July CTP improvements.
Learn more about live events, including web chats, regarding the July CTP.