On November 30, 2006 Apple filed what appears to be a patent for the iPhone, a mobile phone/iPod hybrid that has been rumored to be in development for over three years. In United States Patent Application #20060268528 Apple refers to the device as:
A handheld computing device is disclosed. The handheld computing device includes an enclosure having structural walls formed from a ceramic material that is radio-transparent.
It's pretty interesting that Apple is building the iPhone enclosure from ceramic material (which they call Zirconia in the patent) for "radio transparency." The change from aluminum and/or plastic (like the iPod) may allow Apple to make the iPhone's antenna internal, much like PalmOne did with the newish Treo 680.
In his DiggNation podcast, founder Kevin Rose leaked even more details of the iPhone:
The new device has been described to be as "small as (expletive)".
The new device is expected to run a "mini version of OS X." The new device will ship in two memory capacities, a 4 GB and an 8 GB model expected to be priced at $249 and $449 respectively. The unit is expected to be based on Flash memory. The device is expected to support the major network standards and be without individual/provider network ties. The device is expected to support SIM card support as well as feature a cool slide-out keyboard and touch screen. Finally, the device is expected to support two batteries, one powering the phone functions while the other supports the music-playback/iPod elements. The two batteries will be powered by a single charger.
Another nugget from the patent:
 p. 22 - The battery may be either a rechargeable lithium polymer battery or a lithium ion prismatic cell. These type of batteries are capable of offering about 10 hours of continuous playtime to the device
MyiPhone.com has posted the patent in full text, so that you can easily search through it in a browser. If you're a glutton for punishment, the full patent is also available on the USPTO Web site. I have posted a PDF document (2.5MB) with the complete contents of the patent application (including the drawings) and it's searchable. Great bed time reading for Mac heads.