The UK version of Amazon is right now listing a Game of the Year-edition of Fallout: New Vegas, despite the fact that Bethesda hasn't announced one yet. While there's not many details, the price of the GOTY-edition is pretty fun - you can pre-order it for £20,62, while the regular version of the game is selling for £29.99.
What is actually in a GOTY-pack of New Vegas, if one is actually coming, is of course not known - but if it sticks to tradition, it will probably come with the game and the DLC packs that have been released by then.