I kind of think we should start calling Prisoner's Dilemma programs "Tradebot" instead of Cooperatebot and "Warbot" instead of defectbot or whatever. It more closely matches real life situations that match onto the reward matrix: Trading is mutually beneficial if you both do it, War is expensive if you're both good at it but if the opponent is not prepared for war it is profitable.
CooperateBot has the extra connotation of having no faculties for deciding not to cooperate in some situations, and thereby being completely vulnerable to exploitation. TradeBot doesn't quite capture this, "trader" implies an ability to get ahead, while "cooperator" can be a context-ignoring idiot.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.