Somasegar has blogged about Visual Studio "14" CTPat http://blogs.msdn.com/b/somasegar/. At a CTP it should be installed on dedicated PC with no other version of Visual Studio installed.
There are important updates for both C# (see http://blogs.msdn.com/b/csharpfaq/archive/2014/06/03/visual-studio-14-ctp-now-available.aspx) and VB.NET (see http://blogs.msdn.com/b/vbteam/archive/2014/06/03/visual-studio-14-ctp-now-available.aspx).