Pythonista is a Python IDE for iPhone, iPod Touch, and iPad. It offers syntax highlighting, code completion, and an internal Python 2.7.5 interpreter. You can export scripts as Xcode projects that build standalone iOS apps. Pythonista requires iOS 7.
Pythonista is the most expensive Python IDE in the App Store, but it has a nicer UI than the others. It has scene, sound, and other modules for accessing iOS functionality in order to develop interpreted iPad and iPhone apps. Its greatest omissions are the NumPy, SciPy, and matplotlib modules; these are, of course, popular requests from the scientific computing crowd. The free Python Math app includes NumPy as an in-app purchase, so adding NumPy to Pythonista may be feasible.
Pythonista, omz:software, $6.99