Swizdesktop is a project mainly written in ActionScript, it's free.
Swiz AIR Library
Swiz Desktop Library for the use with Adobe® AIR®.
The library is only supposed to be used in combination with the Swiz framework: http://swizframework.org
Features:
For the update engine the AIR Remote Updater from côdeazur brasil lab is included: http://codeazur.com.br/lab/airremoteupdater/
For further information please check the blog post: http://soenkerohde.com/2009/11/swiz-desktop-for-air-support