Consider including the code for printf or at least make reference to Norvig's IAQ.

def printf(format, *args): print format % args,

It might be worth mentioning here that Python's RE support is via an external module in the standad library - after all, Perl's RE support is an integral part of the syntax which, while powerful, is a lot "messier" than Python's nice tidy module.

I'd be tempted to split regular expressions out into a quick pair of paragraphs on their own instead of just 'dumping' them in here. Its not worth dealing with them in detail at this point, but they're completely irrelevant to printf processing (the context at hand) and there are a few neat (and different from perl) features worth pointing out to anyone accustomed to re. work in the first place.

I agree. The regex comment feels a little out of place.