I also agree that I believe it was Baltar. He was the only person on board that knew the exact number of Cylons Models there were. If you recall, Caprica told Baltar, “There are twelve models. I’m number six.” There was no one else who knew that there were Human model Cylons (except for Baltar, Tigh and Adama, in the mini-series through “Litmus”). And Baltar was the only one who knew the exact number of models. So, since Tigh and Adama didn’t know the exact number of models, that only leaves Baltar. I doubt that the Cylons would program Boomer or another Sleeper Cylon on board to release that information.
