Yes. But Alteriwnet was so much better that I never played on Steam much once it was out. Also, it let me run the game on several PCs on my LAN without extra keys (and DLC).
When AIW went dark, I switched to MW3 (not always bad, lots to like about the game, but cheaters and non-ranked servers suck). I missed AIW. I'd leveled up, mostly without gross XP boosts (a few servers were very high XP), and unlocked everything, and yet still wasn't bored with MW2.
I bought two more copies of MW2 to use with IW4M on my LAN (no worries about steam account logins that way). It is working OK, certainly good enough for LAN parties with mods. There are enough servers, just not enough players to really get things going the way it was, but still better than Steam.