The Hollywood North Report has recently reported a couple of new things about several upcoming episodes. Spoilers ahead:
In the episode Lay Down Your Burdens, what we know so far is that that the Cylons arrive at the fleet with a peace offer, and with Leoben being the one who's bringing the offer to the table. It's now being reported that Number 6 and Boomer will be the ones doing that, as well as a new Cylon model, named Brother Cavel. One of the very early casting rumors was Dean Stockwell, best known for his role on Quantum Leap.
Another casting updated with the episode Sacrifices, Dana Delaney will be playing a terrorist. In this episode, she is apparently the one who lost a husband in the Cylon attack, and takes people in Cloud Nine hostage, demanding that Adama turn over Sharon to exact revenge.
Finally, it's also appearing that Baltar will become President while Roslin recovers.
Source: Hollywood North Report and Trek Web