Not AI, but bots. Many people have made bot mods for both CoD, CoDUO, and CoD2.
So technically you can add bots to MP, by either getting bot mods or making your own.
Beware though, the bots can be as dumb as a door post so I wouldn't suggest trying to have a good game against these poor suckers. You'd win 99.99% of the time.
While they walk around on the maps, they don't really do anything else. They are usually used for mod/map testing.
Here's a site that has some good bot mods:
Just search for "bots" and you'll find 5-10 of them. For CoD2 there is a great bot mod, I believe it's "Ukr-BotsMod" Something like that but It's probably one of the best bot mods out there for one reason:
The bots actually shoot back at you. Beware with this bot mod 'cause they are good head-shooters.
Hope this helps!
edited on Jun. 28, 2007 03:59 pm by djheps