Despite The Elder Scrolls V: Skyrim’s ’Dawnguard’ DLC only being just released on the PC and has yet to be released to the PS3, rumour has it that Bethesda is already working on the next content pack.
G4TV report that Bethesda has filed a trademark for ‘Hearthfire’ which could possibly be the next DLC, however the studio declined to comment about it.
The official paperwork filed with the USPTO indicates that the filing is for a “Computer game software for use with computers and video game consoles; downloadable computer game software offered via the internet and wireless devices.”
G4TV note that ‘Hearthfire’ is a month in the world of Skyrim, and is considered to be the beginning of fall, which in the Northern Hemisphere would be September. Then according to The Elder Scrolls Wiki, the 3rd of Hearthfire is the day of Tales and Tallows, “a celebration of Necromancy,” a day that is feared by citizens who avoid the streets.
The Necromancy theme suggests that the next DLC pack will revolve around the undead.
While G4TV is a respected publication, and this speculation seems to be a fair deduction, keep in mind that this remains unofficial.