Yeah, I can't explain it, but I'm also in the camp that hates when ppl call it the "iTouch." I guess it's kinda the same as when ppl say "warsh" instead of wash, or "warter" instead of water, or "fustrated" instead of frustrated. Saying these things seems to indicate a certain lack of knowledge, intelligence, etc. ("seems to indicate," not "certifies them as a moron"). :-D
Irrational? Perhaps. But it doesn't change the fact that it annoys me.
Actually, it may be irrational to get annoyed by someone shortening iPod touch to iTouch, and yet have no problem changing people to ppl.