I've recently come across a weird bug with UINavigationBars. For some reason, the UINavigationBar "absorbs" any touches that land around 8 pixels below the bar. A good description of this behavior can be seen here:
http://dinhviethoa.wordpress.com/2009/02/14/uinavigationbar-and-touch-events-strange-behavior/
None of the touches will reach any views in the red zone, so the effective touch areas of anything near the top of the screen is cut off. Has anyone figured out any workaround to this problem?