Mono supports a number of platforms, Windows included. For us, supporting Windows is important because it helps us debug our code, helps ensure that we are doing things portably, and is useful to test applications on Mono in Windows and contrast it with .NET on Windows.
Today on the mono-list someone mentioned another use of Mono on Windows (as part of a bug report), which made my day:
It's reasonable to ask why someone should be interested in running Mono on Windows when the original .NET is available. My reason is that Mono applications can be run without an install. .NET requires a lengthy installation (and a reboot with 1.1 SP) that many administrators (if not users) will not consider. Mono can be copied on (or even run from a memory stick).
It is not every day that you run into reasons to run an open source implementation of a Microsoft standard on a Microsoft operating system.
Mono on S390x
In the mean time, in another side of the universe Neale completed the 64 bit port of Mono to the S390x. It is part of Mono 1.1.13.
Aaron posted an update on his work on Banshee, the awesome Mono-based music player that ships with SUSE Linux.
Imeem on Mac
Imeem is the second commercial Mono OSX application that ships.