I ported the San Angeles Observation demo from Jetro Lauha to the iPhone (www.oolongengine.com). You can find the original version here
This demo throws about 60k polys onto the iPhone and runs quite slow :-(. I will double check with Apple that this is not due to a lame OpenGL ES implementation on the phone.
I am thinking about porting other stuff now over to the phone or working on getting a more mature feature set for the engine ... porting is nearly more fun, because you can show a result afterwards :-) ... let's see.