Knights armament has one called KAC I believe. The "military grade" version has trajectory validation. The one iPhone program with that feature I'm aware of.
Roy,
I had problems with the i-snipe program it wasn't inline with the software on my pda and more importantly i was having problems hitting targets with the dope numbers it was giving.
isnipe, bullet flight and ballistic, I own the military versions of both bullet flight and ballistic. they work very well. Ballistic acutally uses the same balistic engine that the JBM website uses. I have never used isnipe.