the competition between AIR and Gears may not be obvious initially because like what you said, Air and Gears are 2 totally different technologies altogether.
But Gears does affect AIR adoption in some ways. Most AIR developers create AIR apps not as standalone desktop apps but as offline versions of a webapp (eg. Twirl for twitter).
So if you are a developer and you want to offline-enable your webapp (eg. Zimbra), you could do it with Gears or AIR. If Gears is already installed on most of your users' computers, you would more likely do it with Gears. (why force your users to download a piece of sofware to run your AIR app?)
I would say Gears is all about extending the capabilities of web apps by adding desktop-like features like local storages while Air is more of a toolset to build cross-platform desktop software easily.
Each has its own strengths and depending on what your solution requires, one of them would be the appropriate technology choice. But since Google has been hammering the point that the web is the platform of the future, i would expect more developers to develop for the web instead of the desktop (which is a major blow to AIR)
But Gears does affect AIR adoption in some ways. Most AIR developers create AIR apps not as standalone desktop apps but as offline versions of a webapp (eg. Twirl for twitter).
So if you are a developer and you want to offline-enable your webapp (eg. Zimbra), you could do it with Gears or AIR. If Gears is already installed on most of your users' computers, you would more likely do it with Gears. (why force your users to download a piece of sofware to run your AIR app?)
I would say Gears is all about extending the capabilities of web apps by adding desktop-like features like local storages while Air is more of a toolset to build cross-platform desktop software easily.
Each has its own strengths and depending on what your solution requires, one of them would be the appropriate technology choice. But since Google has been hammering the point that the web is the platform of the future, i would expect more developers to develop for the web instead of the desktop (which is a major blow to AIR)