Well....GREAT episode....
Anyone catching the theme of Baltar as a messanic figure? It started in Season 3 with the trial, and is continuing with his "apostles" giving him sanctuary, and his plea to the "One God" to take him and spare the "little child(ren)"? Even the physical appearance....long hair and a beard.
So...is Starbuck a Cylon? I don't think so, but I do think she has been captured by the Cylons, and had her mind tampered with.
As for the "Final Four"....I think Anders will reveal himself to Starbuck as a Cylon, even though she has already told him she would shoot him right between the eyes(only half in jest). This will create a great conflict, now that Anders is a Viper pilot.
There is some new speculation that it's Apollo that's the 12th Cylon.....Apollo made some comment in a conversation with Adama about "what if Zak came back from the dead, and we found out he was a Cylon...would it make a difference?" Is that a set-up for a future episode...?
Should be a great final season!!!