SPOILER WARNING
If you don't recall the
Last Supper image, then look back to
http://www.scifi.com/battlestar/.
According to an Entertainment Weekly interview with Ron Moore, Battlestar's Executive Producer, the FINAL cylon is supposed to sit at the empty seat between Tigh and Lee.
This single statement allows us to rule out EVERYONE at the table.
He also says that the symbolism of the poses is very revealing. From Tyrol holding the knife, to Starbuck being embraced by Anders. Everything is significant.