The AirPower mat differs from most other wireless chargers by offering support for charging up to three different devices at once. (Obviously, Apple envisions that those will be an iPhone, an Apple Watch Series 3, and a pair of AirPods, but in theory, it should support any three devices with Qi charging.) There’s an extra level of software on top of the usual Qi stuff that will add some extra animations when you place your phone down to charge, as well as show charge levels of all three devices on an iPhone.
According to MacOtakara, there’s some extra tech working to make sure that the Apple Watch Series 3 can charge, given that the device is typically designed to work with Apple’s own magnetic charging pucks. The report claims that the AirPower mat can detect a specific radio signal that indicates that an Apple Watch Series 3 is on the mat, then enables the watch to charge over Qi — which may explain why finding wireless Qi chargers that work with the Apple Watch is so difficult.
There’s no word yet on the price for the AirPower charging mat, but Apple’s website still claims it will be out sometime in 2018. The March date would also make sense if Apple holds a March hardware event like in previous years; the event could also include new iPads, which were rumored earlier in the week.