I use VMWare Fusion to run Windows XP and FreeBSD on my Mac Pro. To be honest I mostly run in for the single Windows App I can't find a replacement for RegexBuddy.
I'll admit it's an expensive way for me to be lazy. I could test regular expression in the python command line. I'm just to lazy 
Anyway, to get to the point. There is a good google tech talk by one of the authors of VMWare Fusion. He goes in to the ins and outs of OSX development touching on the 'Apple creates API's for it's own needs' which I think most OSX developers know. For some reason embedding is disabled so here is the link.
