antihero898: Sent them three requests, two through technical problems with the game, and one with wanting to possibly get my money back. I sent them the first message a week ago. UT 2004 was meant for multiplayer, how do they think they can sell this without it work? My first impressions of GOG are not going so well.
Unreal 2004 came to GOG whilst it was in beta, and back then there was no method to provide multiplayer keys automatically, hence the request form. You say you used Technical Problems. There is a dedicated option for multiplayer key requests. Use this form and choose multiplayer key request (apologies if this is indeed what you already did):
http://www.gog.com/support/contact/technical_issues_with_games/unreal_tournament_2004_ece Also, GOG are a very small team and being as it is the Xmas sale time they are probably very busy with lots of requests going on, maybe some of the staff are also on holiday, too.
I have seen some newly released games (since the site left beta and became 'release') which provide the multiplayer key in your My Account page. I don't think old games will get this done, though, as many people already asked for their keys, so it would be a lot of work for GOG to track them all down.
The game does work, though, even if it is against bots or on LAN, but GOG will get your key to you. If you do still get a delay with an answer from them, though, then find one of the blue text guys on the forum posts as they are GOG staff. Send them a message so that they'll spot it and they'll likely look into it for you.