I'm loving my iPhone (yes, it's still not "worn off") and I just found a page on the Apple site that is offering $100 off the units (both 8 and 4 gig models).
Some are refurbished, and some are returns or restocks. All come with the standard warranty and the ability to get an extended warranty -- if you do that sort of thing (I don't).
The catch, after much talking back and forth and emails to and from the folks at AT&T, is that they are STILL requiring a two year contract just to use the phone -- even if you have a contract already, even if you are no longer under the weight of a contract, and even if you buy the phone elsewhere.
A more thorough treatment of what I've learned is available on my "other blog".