Hi, How Are You may be the closest thing to a 3D platformer right now. Leap Quest is close, but for me it's more of a 3D Doodle Jump than anything else. There's another game in the works that's a more proper Mario-style 3D platformer, but for the life of me I can't remember the name.
*edit*: @Squarezero beat me to the punch! Our game Leap Quest is one of the few It's more of a platforming hybrid, though - the levels are randomly generated rather than pre-designed like Mario 64. Armado is another one, though I haven't played it. It looks pretty fun, though.
Have you tried Otto-matic: Alien Invasion yet? It's better than what most people give it credit for. Hi, How Are You is good too, although it's a little annoying.
can't remember where i read it, but there's also a game coming out that looks like a proper 3d platformer about a girl with a little raygun. i need to find out what that was called.
Because while the controls are possible, they're annoying as hell. Touchy joysticks, limited to 3, maybe 4 special buttons (attack, jump, whatever, whatever) which you can't actually feel, making you accidentally press the wrong button, and swipe to rotate the camera, which means taking your hands of the controls, probably resulting in you dying.
Otto Matic and Bugdom come to mind. Search for Pangea Software in the app store. I agree about the controls, though. I love the iPhone, but I'd much rather play this kind of thing on a psp with hard controls.
http://forums.toucharcade.com/showthread.php?t=27921&highlight=commander+keen there ya go, kim's adventure, in submission.
Fraid it is, or at least partly is. One of the game modes is even called "platforming" it IS good though. Very good.