Visual Studio 2010 has been out for awhile but really couldn’t be used for development without some workarounds to Debug. Now, not only can you use Visual Studio 2010 but also the additional features and tools within the .Net Framework 4.0 while developing add-ins for AutoCAD 2012.
In fact, the wording used from a reliable source was “Visual Studio 2010 is required to debug .NET applications in AutoCAD 2012 (although .NET plug-ins built using Visual Studio 2008 will load and run fine without rebuilding).” – Underline is mine
For any of us who develop applications for AutoCAD and Civil 3D, this is GREAT news!!