This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
I have done some unittesting of Android apps. I have very carefully layered my app so that the business logic is in POJOs with no dependency on the Android SDK; I test those with standard JUnit test cases. I have also used the Android SDK unit test framework to check the app's UI, but that is often trickier.