My GitHub handle is the same as my HN username. Go nuts. You'll notice I mainly write .NET software but I won't be contributing to MSBuild. MSBuild is becoming irrelevant with ASP.NET 5 and Roslyn.
No. It's also very much not irrelevant if you build non-web software. (I do games with .NET, and that's not going to be replaced by the kproj stuff anytime soon. Which is kind of a drag, I like that stuff, but such is life.)