Adobe Air is probably one of the best inventions by Adobe in my opinion and there are several apps which have made good use of it, take for example Tweetdeck. The best part about Adobe Air is that the applications are platform independent just like Java apps, and only require a runtime to run the app.
Now, Adobe is taking the same platform independent flexibility to mobile devices with the prerelease of the Adobe Air for Android platform, which will allow developers to create applications using the platform and run in natively on the Android OS.
If you are a developer who uses Adobe tools and are excited about this news, you can visit http://www.adobe.com/go/airbetasignup to get a prerelease of the development tools required to build an app for Android.
Though Flex 4 is not fully supported, developers can build Android apps using the Adobe Air platform with Flash Professional CS5 and Flash Builder 4 for pure Actionscript projects.