For those of you of the Android persuasion and looking to interface your device with an Arduino, have a look at the range of tutorials available at mitchtech.They have several well-written and detailed tutorials on using both analog and digital I/O with an Android phone, as well as a variety of examples to work with. For example, interfacing temperature and light sensors:
You will notice in the video that they are using a seperate USB shield with an Arduino. However here at Freetronics we have created the optimum solution - our USBDroid - which contains a USB host-mode controller and a microSD memory card slot all merged together into a single, integrated board that is 100% Arduino compatible. This is the ideal platform for developing peripherals or projects based around Android devices with ADK (Android Developer Kit) functionality, but without requiring a USB host controller shield stacked onto an Arduino.