ncm, bagder: Why don't Windows people help with Free Software projects? I suspect the reason is more practical than what you suggest: developing software under Windows is PITA. A few weeks ago, I spent a couple of hours trying to set up a Mozilla dev environment on Windows (trying to help fix 244770, and failed miserably. I already had Visual Studio and Cygwin installed, but needed the latest library updates, the right directories in %INCLUDE% and %LIBS% and in the right order etc. When I compiled Mozilla on Linux (to fix 128398) I just untarred, configured and built. Admittedly Mozilla is not your average FOSS project, but the point still stands:
Linux: comes with a build environment ready and working.
Windows: requires paying for Visual Studio (or juarezing it) and often installing FOSS tools for development and general futzing around for non-native (ported from posix) apps.
Mac OS X: (badger's comment about "windows dev/user ratio lower than on any other OS") comes with build environment and dev tools (Xcode and the usual FOSS suspects).
Stuff: Need to: look at Bacula for UCC now we have tape library; organise intervarsity LAN with MINCS where much ET shall be played; finish coding Excel/VBA monstrosity for SQM assignment by internal group deadline of tomorrow evening; stop playing around with Asterisk at work and actually put the new PBX into production; work on weather.gnome.org; get daniels to fix 10866 so I can use my new laptop in X; sleep.