Google I/O 2011 contained a lot of really valuable information the problem is digging it out of the huge number of videos that have been made available. To help with this problem here are the videos of the Android sessions roughly categorized.
If you are looking for information on the ADK and the Android Arduino connection it is in the Advanced topics group. There is also an interesting overview of Honeycomb in the General/Future group.
Xamarin has produced a handy cheat sheet showing how app controls differ between iOS, Android and Windows Phone. It makes a fascinating comparison and you can't help wonder why we can't have a standar [ ... ]