This may be old news (about a month old) but I had not heard about it until a friend pointed it out to me.
It looks like Microsoft will, after some mentions of it in early 2014, be ‘open source-ing’ .Net and making official builds of the runtime for Linux and OSX. In my opinion this is great news. .Net (C# in particular) has been by far the most productive language I have ever used; .Net has an abundance of officially supported libraries that make your coding life so much better.
Hopefully the guys over at Mono will be hired to oversee the porting of the official builds as they’ve done a great job so far of creating unofficial ports to other OSs.
It will be a while before we see anything materialise but at least Microsoft have now publicly announced it.
source: .Net for Linux and Mac OSX