I noticed we got the SupCom series added to Gog and am wondering if the 2nd game has multiplayer (LAN in particular). I couldn't find anything on the product page so I'm asking here in the forums.

I was wondering the same thing, I own it on Steam and it didn't have LAN mode there. The multiplayer was done entirely through the steam backend which is obviously going to be disabled in the GOG build. Unless there is some mod which patches it in, I think it is probably only going to be single player.
I would be happy for someone more knowledgable than me to prove me wrong though.

I was worried about that to. The biggest reason to play this is to play with others, and a LAN gameplay component is all i ask for, ill figure out setting up or making a script to enable multiplayer outside of that.

If the dev's are cool with turning over the network source code im totally fine, doing for free, reintegrating MP into the game so that it supports LAN mp at the very least.

Wait, so the supreme commander 2 is not lan compatible even with Hamachi?

There is no LAN option. It was made using Steam API for multiplayer.

gog have actually removed the multiplayer option completely. they might however be able to add it later, as they did for other games(war wind and kknd at the very least). those games however had the option on the menu, gog just had to do some patching to fix it. i suggest asking square-enix to preasure gog regarding supreme commander 2. i will do that myself.

until gog adds multiplayer however, you could play the steam version. it is not that expensive.

This is terribly inconvenient. :(