I honestly doubt that a Mac or Linux version will ever come out.
1. if you where brave enough to use WMP for mac back in the day, Zune would run about the same cause it is based off the WMP engine and would have to run under the same compatibility thus be crap and evil in the amount of bugs. If this would be the case, I can see what little rep Zune currently has with iPod users/the major populations vanish *poof*.
2. It doesn't make any market sense. That's like making a pencil that will only write on 7% of paper in the world. (3% in Linux's case) Development would cost way more than it would ever make. MS should just lean back and let third parties do the work, SongBird, woking on the Mac and Linux, has a Zune add on that will work guys, Zune software isn't he *only* alternative.
3. Just run Windows. I cannot count the number of times that I've heard this, "Wow, now I can run Windows on my MacBook, Macs are going to be able to run anything and they are so much better blah blah blah......" Why not USE the crap that Apple has been bragging about for the past year?
The Zune is a good machine, so is the iPod, so is a toaster, what's your point? Zune 120.