Perhaps the weirdest creature to come out of the iPhone 2.0/3G launch paraphernalia is the iPhone Configuration Web Utility (Mac, Windows). It is a Rails app, downloaded and installed on your local machine. It literally starts a server on port 3000, as a service using WEBrick on Windows and as a launchd job using Mongrel on Mac.
As a side effect of being written for Rails in Ruby, the entire source code is available; just go to /usr/local/iPhoneConfigService/ or drive:\Program Files\Apple\iPhone Configuration Web Utility and dig in. (Also: Open the installer again on Mac and hit Cmd+I if you want to see which files to remove.) The Enterprise Deployment Guide PDF has some more information.
For a more… traditional solution, Apple thoughtfully produced a Cocoa (desktop) iPhone Configuration Utility as well.
Update: An earlier version of this post said that the web app used SproutCore, an assumption I made by comparing widgets to other recent Apple web apps; it’s not SproutCore though, it’s “plenty of Prototype/script.aculo.us”, according to a source who wishes to be anonymous.