PrinceCola: Hello. I am wondering how multiplayer games work when GOG is non-DRM. Let's say i want to play Far Cry 2 multiplayer. How would it work?
Thanks in advance
DRM have nothing to do with multiplayer, neither the client. As long as official servers are up, you should be able to play multiplayer. For some games, you might need the CD-key in order to make your online account and that one will be provided by support team.
Now, what got you confused might be Steamworks. That's Steam specific, there are their servers. You can't take a game from GoG, or other site, for example, and connect at Steamwors. You need to connect through Steam. There are few games that use Steamworks servers, and most of them are exclusive on Steam, you can't play them multiplayer anywhere else. I don't think there is any of the GOG games in this situation.
And about games that do not use Steamworks, but the original servers and they require CD-key in order to activate your account, you still need the key on Steam too, the difference being that you have it provided from when you buy the game and you don't have to ask support for it, like you do on GOG.
I doubt that GOG will have private servers as Steam does. Even for Steam, it's a hassle for some games. Unless they were released with Steamworks, it's not easy to implement it. They did it for Company of Heroes, for example, migrated the multiplayer function into Steamworks when original servers closed.