Lately I’ve been asked several times about how to get an installed version of Adobe AIR updated. After all, applications can update themselves via the Updater API. But what if the new version of the application requires a new version of Adobe AIR itself?
The answer is that AIR will update itself–and has been updating itself since the beta 2 release. If you’ve got Adobe AIR Beta 2 installed and you encounter an application that is bound to the beta 3 release, installing that application will trigger an update of AIR itself to beta 3. This happens in all installation scenarios: via the Updater API, double-clicking on an .air file, and through Badge Install. 
The update happens fairly transparently; there isn’t much in the way of additional UI that’s shown. More time is spent on the progress bar, of course–the update has to be downloaded and decompressed. Users might notice that there’s an additional check box in the UI indicating that the update is going to be applied. Finally, in some cases, an updated EULA may be shown and require agreement.
What happens to all those other beta 2-based applications on your machine? They’ll keep running until beta 2 expires, as beta 3 installs side-by-side.
You can–and should–use the same mechanism to update your applications to the final 1.0 release when it ships. 1.0 installs side-by-side with the beta releases, so your beta applications can continue to run–again, until the betas expire.
 OK, with one exception: Using the Updater API to update an application from beta 2 to a later release doesn’t work on Vista. Sorry about that. It’s fixed in beta 3.