Much of dotnet is going to be open source and some pretty significant tooling with VS.net Community is going to be free for non-enterprise app development. Visual Studio is also getting into supporting Android development.
Microsoft has been going in this direction for years, but it is neat to see things progressing at this level. I also like that they are decoupling asp.net development from Visual Studio. Developers on Windows/Linux/OSX will be able to develop asp.net apps using any text editor like SublimeText and the command line or plug-ins.
I think it's great that Microsoft is making a big push to capture or recapture developer interest.