Sql Server 2012 hit the RTM milestone yesterday 3/6/2012. You can download the express edition or a trial version from here. Full editions Sql Server 2012 should available on April 1, 2012
http://www.microsoft.com/sqlserver/en/us/get-sql-server/try-it.aspx
http://www.microsoft.com/sqlserver/en/us/editions/express.aspx
The new sql express management studio uses the Visual Studio 2010 shell. In visual studio 2010 I have the enterprise application block 5 installed. When right clicking on the databases in the object explorer I was getting an about not being able to load the enterprise application block addin. To solve this I went to the tools menu and selected external tools. I pressed the reset toolbox button and have not seen the error since.