For the last time, Dual Link DVI is a single #*(&ing DVI plug, in fact it looks EXACTLY like the ones on PowerBooks, PowerMacs, and just about every other mac out there that has a DVI port.
This compares the various types of DVI plugs:
http://www.ss427.com/dvi-d-dual-link-digital-video-interface-cable.jpg
Almost every graphics card I know of uses DVI-I plugs, along with your average display (LCDs connected via DVI use the DVI-D part of the connector), and as you can see on a single-link DVI interface, the middle pins of the DVI connector you all know and love is just simply not utilized.
This is how ADC worked while still having a rather similar connector to DVI; It used all of those extra pins for USB signal and such along with a few other extra pins, not to mention the analog pins for the rare ADC 17" CRT. Of course, this is also why they didn't continue ADC support with the introduction of the 30" display.
As you see, Dual Link DVI uses the same old DVI jack, a single connection at that, it just utilizes pins that weren't previously utilized by the video card or the monitor. This sort of stuff aint new either, VGA connectors in many instances have "empty pins" (ever notice them "missing" on your monitor's plug?)
I hope that clears things up a little
Oh yeah, and there are HDMI to DVI connectors that split off the audio output, I'm sure
