This is not the most important question in the world but I would like to know exactly why the Common7 is named this way and not incremented with releases. Is this like the Windows 7/8 version number issues (ie Windows 8 is version 6.2)?
The folder in question (with VS2010) is usually located in either:
%programfiles%\Microsoft Visual Studio 10.0\Common7\
or
%programfiles(x86)%\Microsoft Visual Studio 10.0\Common7\
The first .NET version of Visual Studio was internal version 7.0, so I think they named the folder Common7 based on that. Then later there were a lot of dependencies (probably external, like plugins or whatnot) that used the name Common7 so it would break too much if they changed it in later version.