I speculate the following based on this article in the Chicago Tribune (enumerated for easy reference):
- Something happens to Thrace (Starbuck). She is on the verge of death. While on trial for war crimes, Baltar convinces Lee Adama (Apollo) that he can save Kara with his technology. Therefore, although she is not currently a Cylon, Thrace will become a Cylon. Lee will defend Baltar in an effort to save Thrace, whom he loves (which baffles me cause there is virtually nothing lovable about Thrace).
- Earth is found. Yet according to Moore and Eicke, a major name is removed from the credits. The writers also indicate that a major shift in the show occurs. I think Adama will die, along with the gorgeous Battlestar Galactica, defending Earth from the one remaining base star.