Oh, this thing again; we had a poke at it on the old forum.
It appears to work by selectively magnetically exciting and/or damping the strings (as an analogy, think of it as an electric motor whose constantly-variable direction and speed are under microprocessor control, and the components of which are spread out on a plank of wood). It's a very clever application, capable of quite weird shit, but which may never get into the mainstream.
It's expensive, but that's the fancy 1st version. There'll be cheaper ones later, if Moog can sell enough of the first run to indicate that it's not going to be a white elephant. Many have commented on its similarity to the Sustainer technology, but it has a bit more up its sleeve than that device.
I've been promised a go on one soon, but I'll believe it when I actually get my mitts on it.