For my next "top secret" robot project I need 2 ultrasonic sensors. Playing around with the Maxbotix MaxSonar EZ1, which perfectly matches in size for this task, I stumbled across the following problem.
At the Google I/O 2011 the new Android Open Accessory Development Kit (ADK) has been published. This allows to connect Accessorys to your Android phone and communicate between the Accessory and the Android via USB. The Accessory has to implement an USB Host, while the Android acts as a USB client.