Microsoft regularly operates in mysterious ways (Windows 8, anyone?) with one of its more intriguing — and recent — manoeuvres being the acquisition of SyntaxTree. The company is best known for UnityVS, a Visual Studio extension that allows developers to debug games created with Unity 3D in Redmond's popular IDE. A month after SyntaxTree's integration into the mothership, Microsoft has released an updated version of UnityVS, renaming it to "Visual Studio Tools for Unity" (VSTU), while also removing the $US99+ price tag.
It's great news for Unity developers struggling with the middleware's own quirky version of MonoDevelop and further proof that Microsoft is done with XNA (if you were somehow still hoping it'd resurrect it), but it comes with a dose of bad news. If you are programming in UnityScript or Boo, VSTU drops support for both languages, dedicating itself completely to C#.
An unsurprising move from Microsoft, but that's no comfort to individuals and companies that shelled out $US99 / $US249 with the belief they would be able to debug in Visual Studio in the aforementioned dialects — which remains true, as long as you're willing to stick with versions before the latest.
As a Unity developer myself that exclusively uses C# (and purchased UnityVS before Microsoft took over), I'm glad to have a new version and a promising outlook for tighter integration with Visual Studio. I'm not sure what non-C# devs will do — it's a crappy situation they find themselves in — but playing devil's advocate, Unity itself has focused more and more on C#, as the v1.9 changelog notes:
C# only: C# being the predominant language in the Unity ecosystem - the new Sample Assets are in C#, the Unity documentation will default to C# - we removed our basic support for UnityScript and Boo to better focus on the C# experience. As a result, VSTU solutions are now C# only and are much faster to load.