Bethesda's only just released the Dawnguard DLC for Skyrim—at least on the PC. While there's no PS3 version for it yet in sight, the studio's parent company Zenimax has filed a trademark application (USPTO) under The Elder Scrolls 5: Skyrim under the name of Hearthfire.
The name is pertinent to Elder Scrolls lore, as it's a fictional month equivalent to September. While the expansion has yet to be formally announced, there's a good chance that the game will come out around Halloween—which I'll elaborate upon shortly.
There's little doubt that Hearthfire pertains to an expansion for Skyrim as the company has long ago revealed plans to release large-scale DLCs like Dawnguard to support the game past release. I should add that the trademark was granted in late May, which would place it sometime after the development (but not the QA) for Dawnguard had concluded.
We speculate that the name Hearthfire relates to a Necromancy-related ceremony called "Tales and Tallows", a practice long since made illegal under Imperial law. It remains to be seen whether the game will actually allow players to take on the role of Necromancers, or their undead-slaying adversaries, but we wouldn't put it past Bethesda to release a zombie-themed DLC for Halloween. That said, they could simply go with plain old Draugr, but that wouldn't be half as fun.
Image Credit: Mjuz