Belkin WeMo Switch and Motion
Earlier this year I previewed the Belkin's WeMo home automation kit, a promising affordable app-controlled home automation system now available.
Plug in the switch and the motion sensor, download a free app for iOS 5 and higher, and you can start turning on and off lighting or home appliances from any iOS device. It gets even more interesting once you add a few additional switches ($49.99/each) and start programming automation actions using the motion sensor with IFTTT (If This Then That) (an example I'm working on for winter: walk into the door after 5pm and the WeMo turns on a small ambient space heater). I imagine this could be extremely useful for pet owners, parents of small children, seniors, and people with larger homes...so far, I just use WeMo to turn off the living room light once I'm comfortably tucked into bed!