Lately I've been unable to install any AIR applications on Vista. When double clicking on the AIR file I'd be presented with the error:
Something went wrong trying to install this application. Please install the latest version of Adobe AIR from http://www.adobe.com/go/getair and then try again.
Which looks like this:

So I tried to play along and go download AIR thinking that somehow I missed an update along the way. I was then greeted with this lovely message when I tried to install the new runtime:
This version of Adobe AIR is already installed on your system.
Which looks like this (if you're playing along at home):

The solution was to find the Adobe AIR Application Installer.exe file, mine was located at:
\Program Files\Common Files\Adobe AIR\Versions\1.0\Adobe AIR Application Installer.exe
When you run the installer executable you will be able to browse and select the AIR application that you would like to install and the process should work as expected from there on out. You may have to right click the AIR Application Installer and 'Run As Administrator' if it doesn't work straight away.
A bit of a pain, but I'm glad I can at least install AIR apps again. Anyone know why I can't install them straightaway anymore?