While iOS 5 includes a new feature that allows for initial setup of an AirPort device from an iPad or iPhone, any future tweaking of settings still has to be done from a Mac or PC. However, Twitter user Sonny Dickson found references to an AirPort Utility app in iOS 5's Settings app. Without going into too much NDA-licious detail, I'll just say that I've independently confirmed what he's found, although the relevant link currently goes nowhere and does nothing.
iOS 5 will go live to the public on October 12, and it's highly probable this AirPort Utility app will as well. Its release will address one of the last remaining feature gaps that has prevented "normal" users from going PC-free with iOS devices. Once the app comes out, we'll take a look at it and report on what we find.