Yes, they posted on their forums about the licensing issues: http://forum.unity3d.com/threads/197948-New-version-of-Mono-with-Unity-4-3-Any-additional-details-

Yes, they posted on their forums about the licensing issues: http://forum.unity3d.com/threads/197948-New-version-of-Mono-with-Unity-4-3-Any-additional-details-on-that http://forum.unity3d.com/threads/197948-New-version-of-Mono-... Of course, I find it somewhat amusing that licensing is what prevents Unity from upgrading their C# support, since licensing the Unity source code is something that is also very difficult: We license Unity source code on a per-case and per-title basis via special arrangements made by our business development team. As this can be quite expensive, we do not generally license source code to smaller operations, educational institutions, nor to companies in countries which do not have adequate legal intellectual property protection. http://unity3d.com/unity/faq http://unity3d.com/unity/faq