Apple has released MacBook Air SMC Update 1.0 which fine tunes the speed and operation of the internal fan.
This update is recommended for all MacBook Air systems. The updater application will be installed in the /Applications/Utilities folder. Please follow the instructions in the updater application to complete the process.
The Update requires Mac OS X 10.5.1 or later and is available via Software Update and as a standalone installer.
More info and download link (551KB) here.