Still on the whole trust metric thing, I wonder if another interesting application could be for network games like QuakeWorld.
For those who haven't been following, in the ideal case, network servers would never tell a client anything they couldn't be trusted to know. But for efficiency, they'll *actually* tell you lots of stuff, like where the other players are, when bullets are coming from behind you and whatever else, so that if you turn around, there's no lag while the client fills in the blanks: it already just knows. This means people with no skills at playing the game can write clever clients that let them dodge bullets, and see behind them and generally just plain cheat. Which isn't good.
There are at least two possible solutions. The usual solution is obfustication. Release binary only clients, keep the servers to yourself, make the on-the-wire protocol compressed and encrypted, and generally strange, and just generally hope no one can be bothered working out how to break the system. The nice theoretical one is as described above: just treat the client as completely untrustworthy, and only tell it things the human that's using it is allowed to know.
I wonder, though, if the trust metric here could be useful. If instead of certifying free-software gurus, you certify something more akin to `honesty' or so.
Once you've got a bunch of people certified, rather than trying to certify binaries, you can establish trust pretty easily. After all, no person has to give their secret identification stuff to anyone else (thanks to the wonders of digital signatures and public key cryptography) unlike binaries whose "secret" identification stuff has to be available to everyone who has a copy of that binary.
Possibly linear growth (size of attack versus number of clueless certifiers) is still too troublesome though. Some method of negative feedback may be necessary here, which in turn would probably require more granularity than just `Honest' and `Not honest'. Still, it could be a novel solution to a fairly tricky issue as far as free games go.