Question: Using [PyObjC](http://pyobjc.sourceforge.net/), you can use Python to write Cocoa applications for OS X. Can I write native iPhone apps using Python and if so, how?

Answer: 
The iPhone SDK agreement is also rather vague about whether you're even allowed to run scripting languages (outside of a WebView's Javascript). My reading is that it is OK - as long as none of the scripts you execute are downloaded from the network (so pre-installed and user-edited scripts seem to be OK).

IANAL etc etc.
The only significant "external" language for iPhone development that I'm aware of with semi-significant support in terms of frameworks and compatibility is [MonoTouch](http://monotouch.net/), a C#/.NET environment for developing on the iPhone.