Sooooo... I develop for windows. And though I'm not writing for vista (who would?), I am using the toolchain. Most of which can easily target XP. It's a very nice improvement over what came before. Should I ever have to run my software on vista, it'll probably work pretty well. I suspect that most windows devs nowadays are in the same boat.
<obligatory_apple_fanboy_comment>It's because they're all too busy porting their apps to the iPhone.</obligatory_apple_fanboy_comment>