A few days ago, Microsoft submitted 20,000 lines of code to the Linux Kernel. This code is three device drivers that will make it more possible for Linux to run smoothly in a Hyper-V virtual machine! This is really out of the ordinary. It seems Microsoft is realizing that running Linux is desirable as a Guest OS, but perhaps only to stay in the virtualization market. Previously, there was limited success getting Linux (I think I tried Ubuntu Linux) to boot in Hyper-V (at least when I tried it).
To see the Linux Communities stance on this code, check out this article.