Hi Jojo,
No, I count Quad (4.0) as surround sound, but (do correct me if I've missed something) the support in ModPlug is largely about giving people either the Dolby Surround 'virtual' channel or stereo access to the rear channels, rather than having support for more than 2 channels at once.
In reViSiT Pro, the tracker notation has actually been changed to add a column for depth, in addition to [stereo] panning, allowing composers to spatialise their music in two dimensions (as xxyy coordinates):
Volume: ··· ·· ·· .00
Pan/Depth: ··· ······.00
In addition, there are extra tracker effects especially designed for 4.0/5.1 setups, such as rotation (theta, Txx), theta & depth slides (Wxx & Vxx) and panning/depth column values to address discrete (single) channels (FL,FR,RL,RR,CT,LF).
I love surround sound, but there wasn't really a program out there that's not somehow limited by the convention towards stereo audio, so it was something I was determined to address with reViSiT. So, when I say "first", I'm more referring to the level at which support has been built into the design. I think that was what I was going for with the word "dedicated" [... surround sound features], but perhaps its not the right word ("integrated"?).
'Hope this answers your question!