Until we get to PHP 5.2 and then we can use the __autoload function.
Of course, that would mean that modules would have to be classes, too.
;-)

True. Or true enough. We could add a magic drupal module in class wrapper. The pros will come from namespace separation and transparent includes. The cons, probably, speed. That bit needs to be evaluated very carefully.

Otherwise, it will be trivial to do some kind of a module in a class adapter. Is it worth it? Don't ask me :)