Being necromantic, but I like it this idea a lot! Also, the basic implementation -- inline hemote -- would be fairly easy for Az I imagine. The secondary functionality - picking chars who are familiar with you and more likely to spot your subtleties - could wait to be put in... or it could be based on existing "familiarity" code. If you've RPed a certain number of hours together, the chance you'll spot each other's "signs" increases.
Just a thought. But I agree with Kinaed, I think people have gone the wrong direction with assuming this is all about trying to covertly communicate messages to people, and is just as much about being fully honest in giving info (other than thinks) which might clue other characters into the TRUE motivations of your char. As is, it seems like every char you meet is a Machiavellian performer of utmost talent: I've seen too many characters able to look you in the eye and say one thing with sincerity while intending the opposite.
This kind of deceptive RP is totally thematic for TI, and a good thing, but I imagine leaving more in-emote clues, whose detection is mediated by code, would add to the intrigue.
