One of the new subsystems Windows 7 adds are sensors, creatively called “Windows Sensors”. Through this, Windows 7 will add native support for light sensors where it can help optimize the user experience based on the amount of ambient light in both the operating system and third-party applications.
The cornerstone of this new subsystem is native support for ambient light sensors (ALS) through a generic class driver. Many laptops today already ship with ALS, for example the new Dell Latitude E-series, however all of them require a manufacturer-specific driver. The new class driver in Windows 7 will enable OEMs to just connect the ALS and not worry about drivers.
At the most basic level, Windows 7 has the “adaptive brightness” feature built into the operating system. Whereas Dell ships its own application today for Vista, Windows 7 can automatically control the brightness of the screen backlight based on the available ambient brightness detected.