Why browsers still allow pop-up dialogs, which are favored by scammers, is a mystery that baffles techies. As one user on HackerNews recently complained: "There are still malware and advertising sites ...
I restored a firmware over the weekend, with the latest iTunes (10.2?) on OS X, and I think it was not modal, I think it happened in the track-playing-UI at the top. Wouldn't put money on it, though.