AfterPulse Elite Army is a fast-paced Online Sniper Shooter game for iPhone that you'll love. This isn't a new game, but it's probably still one of the best shooters you'll find.
After an electromagnetic pulse wrecks havoc on the planet a bunch of world leaders panic and start sending out all its military. You're faced with sniping down enemies, restoring order, or letting the world go into a huge conflict.
Again, this is mostly a 3rd person game but they have a pretty great 1st person view for those interested.