In fact, I saw a lot of
Java developers using Mac too. I was thinking like you before, until I finally save up enough for a Mac, then I never look back, it has become my main development companion, as well as for my part-time studies, my company are MS partners, but in the end they also bought a Mac for the development needs, to develop an app for iPhone to work with our ASP.NET web system.
But then you can use Adobe Flash and AIR to develop for iPhone, and you can still use your Windows, so not necessary a change.
Just my two cents.
Regards,
Jenson