I'm not entirely sure that PS is used predominantly on Macs anymore. Mac is a pretty small share of the market and DTP/graphic design is a little more widespread than it used to be. I'd like to see some stats on it. I'm pretty sure Adobe has released at least some products for PC before Mac in the recent past...something they wouldn't do if Mac was their primary target platform. Maybe I'm just misremembering though...

In any case I can't say I'd be too terribly happy about MS buying Adobe - but I know a few folks that would: the guys at Quark, the guys at Corel, etc. I'm not as much a Microsoft hater as some people but I do know that they'll change things in a way I won't much like.
M