Android App Inventor began in the Google Labs in 2010 (or so).  The project/tool was picked up by the MIT Center for Mobile Learning in 2012 after Google decided to 'wind down' Google Labs.  All-in-all, a much better permanent home for this project since MIT is creator of App Inventor's Open Blocks underpinnings and an interesting sister project called Scratch, 

App Inventor is not a traditional programming language or development environment and there are certainly limits to its capabilities.  But it is easy to install and use while providing access to major capabilities of the device (sensors, text/speech, camera, etc).  There is also a growing community of users who have shared some very creative apps.   

The App Inventor development environment runs on Google's App Engine platform, so you'll need a Google Account to make it through installation and use.  The local environment runs on a nice variety of systems - I've used intel Mac (OSx 10.4+), Linux as well as Windoze XP and 7.  The local installation also includes an Android Emulator, so you don't really need an android device to get started.  There is also a pretty good list of phones and tablets that reportedly work with the environment - my goofy Samsung Intercept even works.  

MIT has done a nice job organizing App Inventor documentation - Start @ appinventor.mit.edu/explore/ and follow the "Setup" tab - consumes about 15 minutes and 150MB of local storage.  Follow all steps provided on the setup page including the step-by-step first app using the emulator.  This will take another 15-30 minutes, but worth it - a little different development environment.  

There are plenty of excellent tutorials and videos floating around the interweb,  thanks in large part to popularity in the educator community.  MIT has developed a nice catalog @ appinventor.mit.edu/explore/learn and an impressive gallery of completed apps @ gallery.appinventor.mit.edu - including source code.  There are some amazing submissions from young programmers here!

A few more resources from my bookmark collection: 

• http://puravidaapps.com (includes snippets)
• http://www.appinventor.org/ (University of San Francisco's courses, e-book, videos and more)
• http://android.jwtyler.com/Tutorials.html (video tutorials and useful code snippets)

MIT has pulled together a short list of App Inventor related Google Groups under the 'Forum' tab (currently @ beta.appinventor.mit.edu/forum/).  The App Inventor Coffee shop contains some interesting threads and appears to be active and friendly.   There are also a number of additional groups out there if you dig - some interesting topics ranging from App ideas/requests to internationalization to open source development.

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Enough for now - I hope to publish a follow-on as I transition from App Inventor to Eclipse IDE/java in the future.