Scooper 'Kailem' tells us that Stan Lee was interviewed on the "Filmfreak" radio station when he mentioned he will not have a cameo in X2...
It seems that unlike the original movie, he isn't going to be turning up anywhere in X2. When asked if he had a cameo in the sequel he replied "No, no I don't, I don't think I'm gonna have cameos in the sequels 'cause I think that gets to be a little much. I'm hoping I can have a cameo in the first movie of each character."