Microsoft has released CTP3 of SQL Server Code-Named "Denali". You can download the files from

Download SQL Server "Denali" CTP3 

(You will Microsoft File Transfer Manager)

Express Edition of the same is available from below link

Download SQL Server "Denali" Express CTP3

Read the below blog as well for more information

http://www.jamesserra.com/archive/2011/07/sql-server-denali-ctp3-now-available/