Android has become famous and incredibly successful, so if you want to develop applications for the Android OS then this is the right time as the Android ecosystem is seeing exponential growth and will continue the same trend in year 2012 too, the earlier you start the better it will be in future. Learning App development for Android is cumbersome like with any new thing. Google has provided a lot of documentation on android on developer.android.com and now recently they have launched the official Android Training that aims to help you build great apps easily with example codes and tutorials.
Learn Android App Development 2012 | Start Android App Development
Android Training provides you tutorials, classes, best practices for the Android framework so whether you are starting of a seasoned app developer you will find them incredibly useful. For eg. there are topics are optimizing battery life, designing good navigation, monetizing your app etc.
Visit homepage of Official Google Android Training.