I am a big fan of Scratch and feel that it is a great educational tool that accommodates a large number of different learning styles. Students gain confidence quickly with Scratch and learn tons of very important Computer Science concepts, including problem solving and algorithm development. Scratch helps to make Computer Science accessible to many students that otherwise would not have given the discipline a go.
I really like that the Google Android App Inventor is built using a block programming structure similar to that of Scratch. A student or child of any age will be able to use this tool. I have two elementary age sons that both program using Scratch and I am looking forward to seeing the Android Apps they create.
The Google Android App Inventor will be another great tool to use in schools to help teach Computer Science. Students will really enjoy that they can write useful applications that can run on their phones.
Here are a few articles that provide some compelling justification for learning how to design and create Android Apps.