AIR from Adobe and Google Gears from Google are two products that bring online applications to the desktop. But these products are not the same. AIR is a runtime application and Google Gears is browser plugin.
AIR allows developers to use web technologies to build and deploy internet applications to the desktop. Mac and PC are currently supported. What this means is that a whole bunch of web developers can now leverage the desktop market and also exploit the power of the desktop.
Google Gears is currently in a Beta stage. This product is a browser plugin that allow developers to create applications that work both offline and online. What this technology means is that even with a really bad internet connection, as long as you know what you wish to browse, you can essentially carry entire websites with you provides the are coded to take advantage of Google Gears.
For example how about having a local copy of Wikipedia made available in communities in countries where internet connections are non-existent or spotty? This is now possible using Google Gears.
There has been some talk of Adobe and Google collaborating on both their projects so that the APIs used by both products are consistent so that developers can easily switch between both the products as and when required.