From the GOG page:


Quote
Multiplayer notice: The game's multiplayer mode is compatible with the DRM-free versions of the game bought on GOG.com AND with the versions that use Steamworks via Direct IP.



My post on the GOG forums:

http://www.gog.com/forum/divine_divinity_series/dragon_commander_multiplayer/post4




As Lazare mentioned :

http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=468356&an=54#Post468356


Lar q (the op) mentioned Steamworks features only available to Steam customers. This means online multiplayer.

GOG customers are stuck with direct IP /LAN. This is poorly described in GOGs listing page and I have requested a refund. I wont get one but I have ppushing every button.