It's an old joke from science fiction conventions.
Well I have seen DVI + Optical SPDIF to HDMI converters for about $45-60 in the US on Amazon.com. Assuming you get the sound working on your Hackintosh, which usually isn't too difficult to do, just hook up the optical output on the back + the DVI output on your card and you've got HDMI with audio.
I've been thinking about doing this myself.
There wasn't any problem with it, it just didn't make any obvious sense (thus the non-sequitur comment) and I'm still not sure what it was supposed to mean. Apparently it's some sort of internet short hand for something else?