Put simply: no. RubyMotion works because Ruby and Objective-C are very similar internally, both being inspired by SmallTalk and sharing almost all "core" language features - it allows to run ruby code on Objective-C Runtime. In this regard, python is a very different language, that would be extremely difficult to port, and it wouldn't really feel like python.
Well, sort of. I wouldn't really call it running "ruby code on the Objective-C runtime". Your Ruby code is effectively being converted to Cocoa API calls during the compilation process. RubyMotion has a number of Objective-C subclasses that match back to Ruby objects (for example, strings in RubyMotion aren't NSStrings, but a subclass of them). If you dump the headers out of a RubyMotion app you can pretty clearly see this.
Ruby and Objective-C definitely aren't that similar internally - as someone else has suggested, there's no technical reason you couldn't do something similar for Python. It just happens that Ruby to Cocoa bindings have been around for a while (for some time with Apple support), and as a result there has been generally more interest in carrying it forward.
Thanks! I knew most of this, but for some reason had an impression that ruby was in particularly nice spot to subclass Obj-C classes. I have to agree, you are right, and other languages could follow RubyMotion's model.
I don't think RubyMotion exists because like Obj-C it was inspired by SmallTalk. Well maybe it is, but that doesn't mean it's an insurmountable barrier that would render a similar project in python impossible or "un-python like". C#/.NET got the treatment a long time ago, http://xamarin.com/. It's just that (it appears) no company or OS developer has taken on the challenge of creating the tooling for python.