Badge-installation is a mechanism to seamlessly install an AIR application (and the version of AIR required by the application, if not already installed) from the browser. A large number of applications provide this mechanism on their sites, instead of having users manually download AIR, and then the application.
For instance, the installation badge on the popular Twitter client Twhirl‘s site looks like this:
Badge installation was not available as an installation mechanism with the Beta version of AIR on Linux. With the public release of AIR 1.5 on Linux, badge installation works on Linux as well. However, do note that this requires Flash Player version 10,0,15,3 to be installed – this version of the Flash Player has also been released today and can be downloaded from the Flash Player Download Page.
All applications on the Adobe AIR Marketplace also feature an installation badge.
Here’s a screencast of a badge installation of Twhirl: