Windows 7 no doubt is working strongly towards making the laptop as energy efficient as possible. Have a look at http://blogs.msdn.com/e7/archive/2009/01/06/win...energy-efficiency.aspx and you will realize that the most energy goes into the screen. Windows has power profiles, but when on AC, it can have a great feature to auto adjust the screen brightness as per ambient light.
Wouldn't it be nice, if Windows could use the webcam or maybe a future supported light sensor to adjust the screen brightness to just how much is needed for comfortable viewing?
This will also mean that in the night if you wake up to use the laptop, you will not be blinded by the full bright screen. With the new LED screen, and the screens are anyway more capable for bright displays. Maybe we can make the end user experience a bit better and convenient, while also using up only that much energy that is required.