Don't know if this has been covered anywhere else, but I had trouble setting up "internet sharing" on my MBP. Setting it up was no problem, but actully surfing the net on my iPhone didn't work that way (I have no wifi connection where my office is). However, after setting a password, it does work all of a sudden. Surfing, checking mail, maps, youtube, the whole shebang. If nothing else works, just set a password (a simple one) on your internet sharing, and it could work. It did for me.