yes ADC has been given the axe. better standard, but without market...it's pointless. firewire was lucky to be backed by the video camera segment otherwise it too would have met an untimely demise too USB. they now co-exist, but firewire seems to be losing momentum with the advent of USB2.0.
anyways back to topic, there is no signal loss as everything is digital. there is no converter, it's just a passthrough. the usb and power is routed through the brick. thus an adc cable goes in one side, and on the other you have DVI output and a power cable. far more clutter than ADC alone, but better compatibility with our PC using cohorts.
R.I.P. ADC, you were ahead of your time, or I suppose dead before your time thanks to Mac's market share and the fact you were a propietary tech. I will miss your cable free clutter
(that is of course when I buy a G5 and 30" screen...for now me and ADC are still best friends).