http://www.pcgamesn.com/the-elder-scrolls-arena-free-with-purchases-from-bethesdas-catalog-for-gogs-holiday-sale

Or they just said something about the upcoming sale

You are little late. :P

http://www.gog.com/forum/general/games_that_are_unofficially_confirmed_for_release_in_the_future_part_2/post2428

It's weird, like they talk as if the sale is happening now but says it ends on the 29th. I think either they got the info wrong or posted this way early and the sale is next weekend.

Either way hopefully more Beth games are released next week if there is a sale. xD

I think this has been released early, if it is true. As they do say at the end;
"
peaking of free games, 3D Realms’ sci-fi platformer Bio Menace joins GOG’s collection of 14 free classics, which already includes Beneath a Steel Sky, Ultima IV, Lure of the Temptress, and Akalabeth: World of Doom.
"
Well Bio Menace is not here, at least not yet.

It seems PCGamesN published it too soon.

Amazon (for the US anyway) just also put many Bethesda games on sale... so it most likely is coming.