Thanks to The ODI for the following rumours from his source.
1) Ms. Hawking (Fionnula Flanagan) will be back for 2 episodes
2) Aldo (Rob McElhenney) will be seen again
3) Jeff Fahey may not be Jacob
4) Christmas will be celebrated on the island during a Hurley or Sawyer Centric Story
5) Libby was with Dharma but there is a twist
6) Marvin Candle has something to do with Rousseau's flashbacks but he wont be shown in it
7) Rousseau will pop up in another character's flashback making another big connection
8) "Redemptive" will be the key theme in the flashbacks (Sawyer,Micheal,Locke,Desmond)
9) Minkowski has been cast and will show up on the first or second episode
10) The Christian Shephard Dead or Alive debate will be put to rest in the earlier episodes
Source: THE ODI