You'd be forgiven for thinking you've already read this article. Truthfully, you pretty much already have. The software is the same (App Inventor), the milestone is the same (public availability), even the development status is the same (beta).
Microsoft hopes to use the company's Web Matrix 2.0 tool-now in beta-to lure new-age web developers to Azure, its cloud-computing platform-as-a-service.
App Inventor runs through a Web browser. If you're using a phone, you work with the phone connected to your computer by a USB cord. Your app will emerge on the phone bit by bit as you work. If you don't have a phone, there's a phone emulator included with the App Inventor setup package that you can use instead. When you're done building, you can "package" your finished app to produce an "application package" (Android apk file) that can be shared around and installed on any Android phone, just like any other Android app.