So, what could this fart app provide that the iPhone one couldn't?

Three things come to mind: Stylus support , less restrictive (I guess?) "app store" and multitasking.

The stylus way to beat the iPhone would be to somehow have more precision in the farting. (I'm not sure I know what that means and I'm not saying the things that spring to mind are of any value.)

The appstore guardianship according to Mr Jobs's morals could be used to beat the iPhone with some graphic graphics to accompany the farting. (Not sure I'd really want that though.)

Multitasking...?

In what other ways that might have relevance to a fart app does the N900 beat the iPhone?