This is a very interesting technology that I'd really like to work with. Conceptually it's quite simple. Partially disassemble an inexpensive flat bed scanner and do a couple of modifications to the scanning head. Spending more money on one probably won't improve the image quality. Mount it in a light-tight fashion to the back of a view camera. Obviously you have to take a laptop and some sort of power source for it when you go out shooting.
Each image takes about 2 minutes to expose, the same amount of time basically as required to scan a page. It also occupies a buttload of space on your laptop. Obviously a Firewire or USB2 connection will help things along.
http://www.scannerphotography.com/I learned about this on Slashdot a while back and just started investigating it last week. It's pretty amazing. Produces very good images of static subjects, but once you understand what it does with motion distortion, that becomes pretty cool also. You can do some amazing portrait work with this setup. I particularly viewing the vehicle section of his photo gallery.