I just received a Chinese Arduino Mega 2560 that claims to be made in Italy (certainly isn't). I had a sketch which was working with my Duemilanova that read a bunch of switches using the internal pull up.
This worked, but attempting to do the same with the Mega (odd pins 53-25) results in it behaving as if the pull ups are off (touching them or connecting to 5v they go high).
I retested the sketch with the Duemilanova again and it worked fine.
Does the Mega have internal pullups and are they set the same way? Any other ideas?