Was it the electric kayak at
http://www.kayacht.com/ ?
While the midship mounting of the motor may be an advantage in steering and weight distribution, the idea of cutting a hole in the bottom of the hull doesn't appeal, and having the motor/prop portruding through the bottom certainly precludes paddling in shallows, risking damage to the prop and motor. I should think a simple outrigger attachment allowing the motor alongside would be preferable, since it could easily be removable, or tilt up out of the way, allowing normal kayak use, esp in shallow waters. I have wanted to try attaching a small trolling motor (got one at a garage sale), but, alas, combined weight of me, motor, and battery would likely overwhelm the kayak. If I could only lose fifty pounds, I'd try it.