Those all sound like wonderful ideas, but ones that would be very complicated to implement. The design they show costs around $250, the price of the two consumer grade cameras and the plexi + mounting screws. It is something a student could put together and use in a dorm room with relative ease.
Since locked down, limited firmwares on all consumer grade cameras prevent any kind of direct computer control, and webcams top out at a grainy 3MP with poor optics, you'll have to greatly increase the cost as well as complexity of the system if you want to do it all in software. The Booksnap scanner you link uses cameras that start at 500-600. And you'd have to write the software of course.
Since locked down, limited firmwares on all consumer grade cameras prevent any kind of direct computer control, and webcams top out at a grainy 3MP with poor optics, you'll have to greatly increase the cost as well as complexity of the system if you want to do it all in software. The Booksnap scanner you link uses cameras that start at 500-600. And you'd have to write the software of course.