GigaPan Systems has recently released a new product called the GigaPan Epic, capable of producing photos at extremely high resolution.
The device, which is powered by AA batteries, isn't a camera itself, but rather uses the owners already owned camera to do the work. The camera is placed into the device and is then rotated around to take photos at perfect intervals (specified by the user, to get the desired resolution), and is then stitched together by the Epic's bundled software.
If you want to see what the device is capable of, check out this 1474 megapixel photo from Barack Obama's inauguration.
You can pick up the GigaPan Epic for $450.