I didn't want to bring this question here since the Contest is a Facebook thing. But Facebook wants my phone number to allow me to post anything on GOG's wall and I'm not willing to share that kind of info with it.
What I want to know is if anyone has any idea of when the Contest will be over and we will see the results (i.e.: who won). It was supposedly yesterday's night, but there were no updates there so far.

Its over already, you can only vote for your favourate now.
Taken from gog's facebook page.
"Our inaugural GOG.com Ad Contest is over! We had a number of great entries, and now it's up to you to vote for your favorites! Come to the Facebook page, click on Photos -> Fan Photos and comment on any and all ads you like. The three ads with the most votes by Tuesday night will earn their creators a free game! Tell your friends and be sure to enter our next ad contest if you want to win!"

I got that part Ralackk. What I didn't understand is why haven't we seen any updates on the voting status, since it was supposed to end yesterday.
I mean, there was no update there to tell us: "Authors A, B and C got their games." or "Ads D, E and F were the most voted" or something like that. Of course we can see the votes for ourselves (and can still vote anyway), but I was trying to understand the lack of updates there.

It's on Facebook too now. Horray! I won! :D
I was actually one of the top 3 (second, I think) so I'm happy anyway. :D

Thank you!

Any idea what game you will get with your code?

If I can choose and I suppose I can, I'll get either Unreal 2 or Runaway, since these 2 are the ones awaiting in my wishlist for the longest time.