Noticed this today while reading about GDC 09. For those of you who actually went you may be able to comment more, but Icarus Studios has Dexter at 30fps with 30k polys.
Pardon my douchebaggery, but will the next version of Unity Iphone do that?
As it was mentionned previously, this engine is very custom-built, precisely for this game. This is why it can push the iPhone this far 
Unity delivers a wider range of functions, not as specialized as this kind of rendering engine. Wider means slower but more flexible.
On the other side, the Unity iPhone Team already mentionned they were still optimizing performances for the next build, until I’m wrong.