Zenimax (Bethesda) have registered "Hearth Fire" under "Computer game software for use with computers and video game consoles; downloadable computer game software offered via the internet and wireless devices".
This leads me to believe this is the second Xbox 360 timed-exclusive dlc for Skyrim.
http://tarr.uspto.gov/servlet/tarr?regser=serial&entry=85546517 - Dawnguard TARR.
The exact same method happened for the Dawnguard dlc.
Folks, Hearth Fire is the next dlc.
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http://elderscrolls.wikia.com/wiki/Calendar#Heartfire
Thanks to user Phyber for pointing this out!
You can read the in-game book (Book Nine of 2920, The Last Year of the First Era) about Hearth Fire http://www.uesp.net/wiki/Skyrim:2920,_Hearth_Fire,_v9
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Perhaps this means https://www.youtube.com/watch?feature=player_detailpage&v=DGIgXeGC6Dg#t=106s from the GameJam?