Michael,
I don't think any company will port any commercial sim on Mac any time soon. Probably, there are multi-platform sim projects, which can be ported by yourself--something like Flightgear:
http://www.flightgear.org/

I work in a company which makes multi-platform software, and Mac has always been the biggest pain in the $%#...
The problem isn't in the Mac itself, but rather in the lack of solid development tools. Hopefully, this will change as MacOS X gets momentum (if it ever gets it).

Boris