Well, Roslin revealed her cylon nature once again in this episode (tigh me up, tigh me down)when she didn’t want to be tested, and diverted attention from herself by placing the focus on someone else and crying cylon. 
They managed to fool the president with the bait and switch plan, allowing them to beat the cylons with their false information. When the president learns of a detail she was not told, which turns the battle, she gets upset. Doesn’t seem normal for someone in her position to sweat the details as she clearly does here.
Early in the episode the cylon plan for the cancer is revealed, when we learn that they are able to have her fulfill the role of an ancient prophecy in the human religious text, which predicts that there will be a great leader and prophet that will save them all.
This will allow her to further spread the cylon agenda further outside the role of presidentby allowing her to be a prophet as well. This way she may also be later given to conversion and teach of the “one true god” the cylons talk about, as this sounds like something a “great prophet” may do.