Adam Kennedy's announcement tells the long story, but the short version is this: Microsoft will be providing every CPAN author with free access to a centrally-hosted virtual machine environment containing every major version of Windows.
It will be interesting to see how this plays out. Will CPAN authors use the resources from Microsoft to make sure that our modules work on Windows? I know that I'm especially interested because I want ack to be transparently cross-platform. Anything I can do to help get ack out on Windows boxen, to help Windows programmers know that the command-line can be better than an IDE, is a win.
This is pretty big, and I'm glad to see Microsoft providing this service. I'm especially thankful for Adam putting what I'm sure was a huge number of hours making this happen. I'm glad we have him on our side.