well Snoopy does "talk" by using a typewriter and the words appear over his head as he types but he doesn't talk like Brian Griffin on Family Guy.
And now that I think about it, Wile E Coyote does talk in at least one cartoon, I forgot the name of it but I think it was a half hour tv special and it's somewhere in the Looney Tunes GC. I think I've yet to see a short where he talks, and I dont consider holding up a sign to be talking.
I think I do remember the episode where Maggie said "dada". Nobody else was around to hear it, so more than 99.9% of her communication is done non-verbally.
and to nitpick the other one from my original post, Dee Bradley Baker is credited as the voice of Perry The Platypus, although Perry doesn't actually talk. The only sound he ever makes is some wierd teeth chattering sound (0:30 on this video http://www.youtube.com/watch?v=EhQ75vyhmc8