Mhhh, Dan's post started well but turned into an advert for Varium, Does that mean that the VArium 3D engine is going to be released for general use ? doubt it.
Anyway if you don't want to write your own engine and you don't have $30,000 to spend but you do have a couple of months to work out how to use PocketGL then that's the way to go. It's fast & quite close to opengl in some respects. At lease I have been able to convert some opengl tutorials quite easily.
The big down side is lack of support & no docs other than the sample source code. That's why I say you need a couple of months to learn all about it. I put up the board at to allow users to communicate (sorry it has popups as my subscription just expired)
PocketGL is $49 and anyone reading this please note you cannot get a copy from me for free before you ask

It's produced by Pierre Leroy and is on sale at PocketGear