mashintime: I’m in the same predicament here. I submitted a support ticket more than a month ago requesting a CD key, and submitted another one a few weeks ago. I have yet to hear anything from the GOG support staff. I was prepared to wait a little while for the key, but waiting over a month (with no response at all) for a key is absurd. I could of purchased the game used and had a CD key in this amount of time. This was my first purchase on GOG and will likely be my last. I’m very disappointed in GOG.
It would be very silly to completely dismiss this site based on one issue. Especially for an issue that's not even GOG's fault. Keep in mind that this game out in early 2004 and Ubisoft didn't exactly contemplate the concept of digital distribution back then. Ubisoft had employed this simple system of requiring a cd-key for multiplayer because back then, they didn't think they would sell their games digitally. It wouldn't be until late 2006 when Ubisoft had released their first digitally distributable game, Dark Messiah of Might and Magic, on Steam, and another two years before they sold anything else digitally on that site. The fact that this game is on GOG means that Ubisoft signed a publishing deal with this site too, and hence provided them with, at least what they thought, all the required materials for the games on here. Now according to the forums, this problem can in fact be fixed, so all I ask is that you have faith. Remember, part of being 100% drm free is that you shouldn't have to memorize cd keys.
One more thing, remember to check your game documents for they might provide a solution as well.