F# has been open source for quite a while. I'm guessing they are seeing some resistance to adoption due to the affiliation with Microsoft. They've always been quite independent, compared to the C# team, so I wonder what this even means. Porting to LLVM and/or JVM would be wonderful for the language though, it really is up there with Clojure as one of the more exciting functional languages under development.
I don't think this is any technical change. Instead MS just got bored with F# and gives it a non-profit ("F# foundation") for maintenance. So it will be independent, ie. not affiliated with MS.
The F# Foundation is an initiative from the F# community to promote F# as an independent, open source language across multiple platforms. You're right this is not a technical change and the foundation is independent.
That's not quite right. A choice quote from the kick-off call today helps explain more about what's going on here: "Some customers require Microsoft support in order to adopt a technology; some customers require community (non-Microsoft) support in order to adopt a technology."
You can think of the F# Software Foundation as the community side of that equation and, well, Microsoft as the Microsoft side of that equation.
MS is not abandoning F#. This is a community-led effort to try to increase adoption of an excellent language and to create a better experience on non-microsoft platforms.
Who is "they"? Mono was transferred from Novell to Xamarin some time ago, but is alive and well (better than ever?): http://mono-project.com/Main_Page.
