Old world blues:
-big empty
-loads of pre-war tech
-hopefully a new set of power armour
-more background to the player character
Honest hearts: (best name out of the lot i might add

)
-Burned man
-slaves telling more stories about the burned man again...
-MORE background to the player character
-hopefully more of a background to the legion so people can understand them more instead of seeing them as raiders :'(
-more faction armour
-A HUGE HUGE HUGE amount of detail being the burned man and how he survived: Being burned and set into the grand canyon and 7 first recon sniper kills (according the chief Hanlon)
There's supposedly a "Lonesome Road" DLC coming out. My guess it involves:
-Clearing the wreckage (dynamite?)
-A bunch of quests
-Side quests
-Battle of the Divide.
-http://fallout.wikia.com/wiki/Ulysses
Added that last bit in.