If you're looking to jump into the iPhone world, now might be a good time. AT&T is again offering refurbished iPhones on its Web site, but this time with even better deals.
The 8GB iPhone 3G can be purchased for just $99, and both 16GB iPhone 3Gs (black and white) can be had for just $199, the regular price of the 8GB phone. Nice upgrade.
These prices are, of course, coupled with two-year contracts, so they're not for everyone. But if you were going to make the switch to AT&T anyway, this might be the way to go.
Refurbs are generally exchanges from previous iPhone users. They're tested, repackaged, and resold at a discount. Usually they have the same warranty as a regular phone. You can check the serial number with Apple to see how much longer the warranty on your iPhone is.