So, when asked if I wanted to actually take on the challenge of building one, I obviously responded with a definitive yes. Even though I personally don't own a lawn (my backyard is concrete and weeds), it seemed like an opportunity too good to pass up. In terms of actually using it, I found a willing victim in Glenn Derene of Popular Mechanics. He was more than happy to let this thing loose on his lawn (along with a slew of other robotic lawn care contraptions). So one fateful day last summer, I tightened the last bolt, wrote the last line of code, packed it up safely, and shipped it cross country to meet whatever fate lie in store.
Albeit I only later saw a video of it in action, it is my understanding that it performed about as well as you would expect an experimental DIY seed spreading robot to perform on its initial run; in short, not very. Rather than a cross between Wall-E and Johnny Appleseed, it is more of a cross between Johnny 5, and the groundskeeper in Caddyshack.
Nonetheless, I think the structural design of the robot is solid. If the code is tweaked a bit, and the rangefinder repositioned, I think this robot could spread seed like a champ.