The latest Chirp to drop through my letterbox included a NATS DVD with a video about the new mode S capabilities (as well as the primary one about level busts). Altitude readouts are only the start of it, with selected altitude, heading, rate of climb/descent, and IAS also being datalinked. The video suggests that all this is coming on line imminently and that all transport aircraft will be fitted with it soon, although I haven't checked up on actual implementation dates.
So Big Brother will be watching you!!
