BrightnessSync

When you own a MacBook Pro with a Mini DisplayPort and a LED Cinema Display, you have noticed that you can control the brightness of the internal display of the MacBook Pro with the brightness keys of the keyboard.

And in the Displays preferences, you can enable automatic brightness adjustment when ambient light changes for the internal display. To modify the brightness of the LED Cinema Display, you always have to use the Displays preferences, and the brightness of the external display can't be adjusted automatically.
BrightnessSync is a preference pane that eliminates this shortcoming: it enables automatic brightness adjustment for both the internal and the external display. And because the LED Cinema Display is more brilliant than the internal display of the MacBook Pro, BrightnessSync lets you set brightness levels for different ambient light conditions for the two displays independently. With this, there is nearly no need for manually adjusting the brightness for one of the both displays.
BrightnessSync was only tested with a MacBook Pro and a LED Cinema Display. It might not work with other hardware configurations, esp. with external displays that don't support software brightness control.
BrightnessSync is published unter the conditions of the GNU General Public License. The source code for BrightnessSync is included on the download image.
What's new in this version:
Automatically adjusts brightness when the Mac or the display wakes up from sleep.