I've never heard of any discussion about doing this. I suppose at the very least, Rhino for Mac would have to be released first, and that's been going on for years.
Personally, I would rather see the madCAM programming resources go into making it a better program for Windows. Like it or not, Windows is the most prevalent desktop OS in the world. It only makes sense to cater to the largest market. I hear the argument all the time that Macs are better than PCs, but at the end of the day, you need to use the tool that works for the task at hand. I could buy an awesome hammer, spend a lot of money in the process, but it's going to suck for turning screws.
l don't really have a definitive answer.
Dan
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)