This trick requires a Mac running 10.3 or later and the latest Apple Developer Tools. Be forewarned, however. The author recommends a dual processor Mac running 10.4, as compiling KDE and x86 from source took the better part of 8 hours. So make sure you've got the day free. With that said, have fun! Let us know how it goes if you try this out.
(Via The Unofficial Apple Weblog (TUAW).)
I installed parts of KDE when I was running 10.3, and it took the whole night to compile, and a better part of the next morning. I think I wanted to compile quanta or something, but I don't remember. It was fun running Safari and Konqueror side by side! :)
I don't think I'll do it again, I seem to be running short of hard drive space these days.