I remember it felt like AGES for the Mac version to come out -- my friends with DOS/Win machines were playing and of course I was out of luck, still clinging to my precious WarCraft 1 in the meantime (apparently the Mac vers came out 8mo later)... I remember visiting a couple friends and playing the game at their house and being so jealous they can just play this amazing game any time. WC2 was such a leap forward and such an improved game (though I did miss the gritty/darker feel from WC1). Great memories of playing modem games with my friends in the area, and AppleTalk LAN games as well of course.
I get nostalgic thinking about WC2 on the Mac. I was a teen then, and loved Blizzard for putting the effort into a Mac release. I don't remember how I found IRC and #macwarcraft, but between dial-up internet, coordinating games on an IRC channel, trading IP's, and submitting game results to manual leaderboards, clan wars, trash talking, etc. What a great time it was :)
None of my PC friends had any kind of networking, but on our Macs we had an AppleTalk (PhoneNet) network between 3 Macs (WC2 ran on a 25 MHz 68040 so my old bedroom Mac would still suffice) making my home the WarCraft II gaming nexus.