The upcoming (next week) iPhone version of Doom, Doom: Resurrection, will not be a first person shooter as I first thought.
What it will be is an 'on rails' shindig similar to the upcoming Wii port of Dead Space. So what that means is that you have no control over your character's movement in the game, he just trudges along a predetermined path while you make with the shootin'. This might actually fit the iPhone better than a fully fledged FPS, but it still takes a lot of the excitement out of the game for me.
Can't have everything I guess.