There have been a few arcade flying games announced and released for the iPhone, but none that I'd really classify as must-have's.
The makers of Downhill Bowling [App Store] are taking their shot at the genre with this as-yet unannounced game:
The game involves two modes: Arcade and Race.
In Arcade, you basically try to shoot down as many enemy targets as you can to get the highest score. Ships spawn crates (yes, good old crates) which you can pick up and drop on a specific target for additional points.
In Race mode, there are 9 different courses where you have to fly through a series of hoops in sequence. We use the same mechanics (shoot stuff down, pick up and deliver crates) except that it gives you a time bonus.
The game is expected sometime in February.