I got this iMac open-box (no-box, actually) in April, but don't need it anymore.
It's got AppleCare on it through April 8, 2011 which means you are covered for a long, long time.
I upgraded the unit to 4GB of OWC RAM and installed a Western Digital 640GB SATA hard disk so that it is pretty much ready to go for almost any power user's or home user's needs.
The unit came stock with an 8x SuperDrive, 128MB ATI Radeon X1600 video card, and the 802.11n AirPort Extreme wireless card. Specs have it listed with 802.11g, but the 802.11n enabler will be installed on the machine. It also has Bluetooth, built-in iSight, and all of the other funness that these machines had stock. This unit has the original matte LCD, not the glossy LCD that the current units have. The color is generally a LOT more accurate on matte screens than on glossy ones.
I don't have the original master disks for the machine, nor does it come with keyboard, mouse, or Apple Remote.
It will have OS X 10.4.11, iLife 06, and all available software updates installed on the machine with a freshly zeroed hard disk. All software will be what it had from the factory, and I will not install any pirated, shady, or non-legal or non-licensed software on the machine. Don't ask.
Looking for $1000 shipped OBO. Local pickup in Orange County, CA preferred, though.
Here's the official spec sheet from Apple (it's the MA590 model):
http://support.apple.com/kb/SP28