[ijk]

Which might be why this version of Unity updates to MonoDevelop 4.0.1.

[saidajigumi]

MonoDevelop != Mono. MonoDevelop is a standalone application, the default Unity code IDE. No doubt an improvement (at least for folks who don't switch Unity to another editor entirely), but not a change in the Unity C# runtime.

[ijk]

Checking the forums, it's indeed only an update to MonoDevelop. I stand corrected.