Then there's the Slide (pictured above) which relies on interesting physics to support the iPad: a heavy high-friction rubber cylinder is pulled out of its tubular compartment under the metallic slope, and it can be placed anywhere on the slope to support the iPad at any desired angle, up to somewhere around 70 degrees -- you can see it and the others in action in the earlier video.
Another major difference is that Palm's dock uses magnets to line up and secure the handset, and LG's accessory relies solely on the friction between a rubber ring and the glass back of Google's flagship phone.