Funny you should ask Gary! Just recently on macastronomer yahoo
http://groups.yahoo.com/group/macastronomer/ (look thru the links) out of the blue a talented aussie programmer, Rodney Kennedy has joined and he has created his own front end for Keiths Image Stacker 'astro yacker' and has a second version yet unreleased, and some other yet unreleased dedicated astronomy progs that have got everyone drooling - see here for his webpage and results -
http://homepage.mac.com/astrod/Sites/gallery/main.html
I dont know about using PC emulators too much - I never liked virtual PC that much, plus as people say PC's are so cheap why would you bother with that when you can have a cheap PC dedicated to that job. Things are afoot in the mac world as well with the imminent release of the mactel macs - althought these will only be in lowend stuff - laptops and the mac mini, imacs - they will never put a G5 chip in a lappy now. They are basically going after dell, I read, but they alledgely can boot up and run from both Windows and mac OS's.
Wish I could endorse the mac as an astronomy friendly platform, but outside of Starry Night and CS/PS, the rest is just flaky and/or not fully formed to me. Their are other webcam/stacking programs like Lynkeous and another one - but i wasnt impressed.
As Steve said and a mate of mine said - if you want a program that doesnt exist currently on the mac, it would certainly exist in UNIX that would fit the bill, but you wouldnt have a dummmy friendly interface/GUI full of shortcuts and automated workflows unless you make it yourself - and you might have to even port it yourself, but that is changing everyday.. wish i could recommend mac as astro friendly - but i would be lying.. but for PS and everything else it rox :-) As for recompiling pc proggy's using wine - i havent heard much about that from real mac people - they dont like stuff that wasnt native X to start with. here is yet another PC emulator for the mac
http://openosx.com/wintel/ dont know how good it is. here's a collection of relevant links
http://www.macastronomy.com/