Probably the most immediate winner is Unity. They've been stuck on an ancient version of Mono because they did not want to license tech from Xamarin. They can now have MS derived runtimes free.

Unity has been developing their own runtime for a while now to get away from the mono licensing costs of using a new version. I'll be interested to see how they react to Microsoft open-sourcing a lot of stuff they might have been able to use.

Wow, didn't even think about that. Huge step for the Unity project.

In terms of velocity and trifty syntax F# is almost as nice as these dynamic languages. It can even be used for scripting.

Not much, I imagine. .net's been supporting languages like that for a long time through the Dynamic Language Runtime. Although, if more people use Iron(Python|Ruby|Scheme), the underlying runtimes, and quite possibly the DLR itself could see some code contribution loving.

I am hoping to hack a bit on the runtime to add some missing features to IronScheme (read: proper continuations!).

I'm hoping ClojureCLR gets some more attention now too.