What do photosensors have to do with power design?

OK, granted, sometimes I write about non-power technology just because it's so cool, but photosensors are muy important in creating power-miserly consumer designs: Photosensors allow you to tailor your display backlighting to ambient conditions, rather than assume worst case and waste battery power on an over-bright display. Speaking as one who spent a lot of time outside squinting at a cell-phone throughout an excruciatingly hot Silicon Valley weekend (and humid too – what's up with that??), it would have been much more useful to have a brighter display than when I'm in an office setting.

The ideal photosensor for this application has a spectral response that's the same as the human eye, and is temperature compensated (rather than varying wildly during those hot summer afternoon, as will uncompensated silicon-based photo optics). Intersil just released the ISL29001/2, which in addition to these features integrated a 15-bit ADC as well as a current amplifier and a 50Hz/60Hz rejection filter, to get rid of interference from ambient fluorescent lighting. They cost about $1.30 Intersil also touts them for motion sensors and proximity detectors.