Your comments

Mr. Grillo's "Pressing Tab would be the same as touching the top-most suggestion on the list." and Mr. Blach's "I think it makes little sense to use these arrow keys if you can just directly tap on the entry." seems awfully confusing if this program indeed caters to those who expect more accessibility than GUI-centric users and eagerly await improvements like support for external keyboards.

Those who can't navigate a page of text without the use of trackpad, mouse or touching the screen wouldn't understand and should disregard the above comment. Please excuse me.

Code completion is awesome the way it is with the arrow keys and return. I agree that the tab key should be put to better use, perhaps with a modifier combo (sans keyboard support through iPad's multi-touch?), or in a Textmate-like way that would allow 'smart' cursor navigation.