Obviously, over on Guildwatch, we've been covering people shouting out names and guilds on the forums for a while, but as we've also reported a few times over there, that barely helps -- even if people do remember a ninja on their server, one name change later and they're gone. A few guildleaders over on Jubei'thos have tried putting a site together to track known ninjas on the server, but even that has issues; it's tough to avoid false positives, even if you do require screenshots.
But surely there must be a solution, so let's put our heads together: a debuff? Something like the group vote-kicking system that's coming in patch 3.3? If Blizzard wanted to really go for fair, they could just take the Need-before-Greed system and turn it into straight Need: if an item matches your class and spec, you get a roll (with items everyone can use giving everyone a roll), and the best roll always wins. You can turn it off (for a Master Looter-style raid), but for PuGs, why even bother with a Need/Greed difference? What do you think?