While I hate to say something that would be interpreted as being "biased against", I agree with a lot of others here that the best way to include MAC and *nix users is to *not* segregate them.
Fundamentally, any problem or solution for a computer is a problem or solution for users of all varieties of OS/hardware. So I'd say, for discussion purposes and all of the stuff that comes *before* the coding, we should not break out into little groups that have a high potential for fracturing the community. It's worth pointing out that I've seen little to no "camp-ism" or what others have termed fanaticism, here at DC.
Perhaps it would be worth a discussion forums for coders, once they get down to the brass tacks of coding, but even then, I see that as a method of segregation. Like others, I'm always interested in hearing how others implement ideas on other platforms - quite often it sparks creative approaches I might have not otherwise thought of, or an exercise in Google-fu to find something new and interesting!
If you feel the need to skip less than relevant topics, we could always try a message header procedure where a simple [MAC] or [DEBIAN] or whatever style slug at the beginning of a subject line when posting, could help others winnow what they are not interested in. But frankly, in my mind that's still a type of segregation that I think we could do without.