I am working on this Android application that needs to communicate over USB. I have an Archos 101 Tablet (specifications here: http://www.archos.com/products/ta/archos_101it/spe
There is a solution by Inopiaaardbei using Arduino and a USB host shield with an Android Debug Bridge running on Arduino.
Using this solution you can use serial communication between the Android phone and the Arduino board.
See my post and the link inside for more info.