So, they announced a pretty cool thing yesterday in the Open Accessory Development Kit (ADK) - a hackable little device based on Arduino and compatible with the Android platform. They talked about using it to do all kinds of things from turning lights and appliances on and off to using your phone as a gyroscopic controller for robotics.
This lovely screen-grab above is what you’ll find at the link provided in the Android documentation to buy the Arduino board that is the ADK. Not only are you told, “Sorry for inconvenience to buy!! The first lot of set are sold out,” but the majority of the site is not localized.