Bethesda Trademarks “Dawnguard”, Upcoming Skyrim DLC?

Game Informer stumbled upon a new “Dawnguard” trademark filed by Bethesda Softworks parent company ZeniMax Media, which they seem to think might be related to an upcoming set of DLC for The Elder Scrolls V: Skyrim. Of course, it could be a full expansion, a new tablet spin-off, a line of comic books, or something else entirely:

Bethesda parent company ZeniMax Media filed a trademark in February for “Dawnguard” relating to video game software, including downloadable content. The application does not specify anything else, and doesn’t mention Skyrim specifically.

Speculation tabs Skyrim because of the Mythic Dawn cult in the series, as well as the Redguard race.