I'm sure to open a can of worms here, but looking back through some secrecy posts I came across this:
Any form of communication besides verbal and in the presence of all players is in violation of the game spirit.
I have to agree with the spirit of the above but not the letter.
It seems to me that secrecy rules have two effects: 1) prevent players from absolutely knowing whether or not a person is human or cylon and 2) prevent players from automatically defeating crises, skill checks, etc.
Now, their is alot of body and verbal language in this game. Technically, a person can say they can add "alot" to a skill check. If they say it definitively, then it's reasonable to assume they can beat it on their own. Likewise, humans can ponder things and ask for certain help such as "If I XO you, do you have any max firepower cards?" A revealed cylon could tell another, openly, "hey, on your turn play your super crisis and then I'll do a fleet activation."
This brings me to what I disagree with. I agree that any non-open communication should be banned. This includes note-passing, texting, playing footsie or even codewords. However, I think non-verbal communication that can be recognized by someone paying attention should be allowed. For example, in a recent game, I was an unrevealed cylon. The revealed cylon was about to play their super crisis card at a bad time (one away from a jump). I tried to catch her eye and shook my head slightly. If anyone had seen it, they would've known I was a cylon. Likewise, in another game, I looked across at the guy I thought was a cylon and nodded to him knowingly to see if he would nod back, revealing to me he was a cylon (I was human but wound up a cylon). To me this is the same thing as openly accusing someone ("he played a basestar, he's a cylon!"). BTW, I'm a tricky bastard.
In addition, once Cylons are revealed they are no longer on Galactica. They should be allowed to discuss strategy in secret as long as they don't violate the secrecies rules (per number 2 above). The humans still cannot, IMO, because even if ALL Cylons are revealed, the actual characters don't know that (just the gamers). Likewise, I need convincing that an unrevealed Cylon can't indicate (in some potentially noticable manner) to a revealed Cylon who they are. For one, I could see using that tactic to convince a revealed Cylon not to something because I was, in fact, human.