SQL Server 2012 was released about a month ago:
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:
Download link: Tabs Studio v2.7.0.