No, the PS3 uses USB audio devices for voice chat only. (Exception: Sony's own wireless PS3 headsets. They seem to have set those up so that if the PS3 detects a USB receiver for one of those headsets, it'll mix the game audio, with optional virtual surround of some sort, and then pipe the two mixed channels to the headset. Those headsets are just stereo devices when used with PCs.)
This is strictly in regards to voice chat mixing, and for PS3 use, I can just keep the otherwise much more versatile SU-DH1 with its Dolby Pro Logic II and DTS decoding capabilities. (Even AAC, though I've never encountered any bitstreamed AAC source material.)
RGB = Red, Green, Blue, yes. In fact, VGA is RGB with separate horizontal and vertical sync. (Some RGB-capable systems have a composite sync pin, or in the case of most Sony hardware, put sync on the green signal.)
Do note that component video has RGB-colored RCA plugs, but is a color difference format (Luma/Y, Red Difference/Pr/Cr, Blue Difference/Pb/Cb), NOT RGB. That's why you need transcoder boxes like the CSY-2100 to convert RGB to component. (Most modern HDTVs throw fits with 240p RGB signals transcoded to component, though.)
And you're right, that's insanely expensive. That's why the discovery of this capture card is such a huge deal for videophile retrogamers.
Oh, and a question for Mad Lust Envy: got any plans for a Slyr vs. PC360 comparison?