Bethesda's parent company ZeniMax Media has filed a trademark to protect something called Brink on PC and consoles.
Specifically, it relates to "computer game software for use with personal computers and home videogame consoles" and "downloadable computer game software offered via the internet and wireless devices", according to GameSpot.
There's also talk of "entertainment services, namely, providing online interactive computer games and providing information relating to electronic computer games via the internet", suggesting an online game.
Could this be the MMO that ZeniMax pinched Dark Age of Camelot creator Matt Firor for? We've not heard anything about that, or the company's MMO specialist outfit ZeniMax Online Studios, since 2007.
Another possibility is the game currently being made for ZeniMax by Enemy Territory: Quake Wars creator, Splash Damage.