SQL Server 2012 was released about a month ago:
SQL Server 2012 Management Studio splash screen
The new management studio uses Visual Studio 2010 shell. Extensibility for SSMS 2012 is still not officially supported by Microsoft, but luckily Visual Studio add-ins work just fine in it. Unfortunately, Visual Studio extensions don’t work as ssms.exe contains white list of allowed package GUIDs. I had to change my Visual Studio 2010 helper extension to helper add-in and after that Tabs Studio works without problems in the new IDE:
Tabs Studio in SSMS 2012
Download link: Tabs Studio v2.7.0.
Tabs Studio Blog (organizing Visual Studio document tabs) 