You can get it from Adobe.com or from updating your client.
Quote from Adobe:
The Adobe® AIR® 2 runtime enables developers to use HTML, JavaScript, Adobe Flash® software, and ActionScript® to build web applications that run as standalone client applications without the constraints of a browser. Adobe AIR and the Adobe Flash Platform unleash the creativity of designers and developers by providing a consistent and flexible development environment for the delivery of applications across devices and platforms. Support for additional platforms, including Android, is under development.
http://www.adobe.com/products/air/
I've upgraded, works nicely.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2.6) Gecko/20100625 Firefox/3.6.6

