Can Drupal run on the iPhone?
Well, not yet, but perhaps soon.
A while back Karoly Negyesi (chx) posted on what is the smallest platform that can run Drupal. He ended up with the Nokia N800 internet tablet as a candidate for that, using maemo (a Linux distro for that platform, which includes PHP and lighttpd). SQLite will be the database.
How far can PHP and SQLite be?
That would a cool, but perhaps of limited practical use aside from demos on the run ...