[Reelin]

Not if it's built into the communication platform you happen to be using. Just one or a few basic indicators to give you even the slightest bit of information about who wrote what you're reading. Just a simple "p = 0.03 US resident" or an aggregate trust score based on a combination of social graph connectivity and spam reports or something. Sure, people could intentionally ignore it, but right now there's no indicator to be had even if you want it!

To be clear, I'm not talking about present day clunky GPG web of trust with key signing parties and all that. I'm talking about a hypothetical (ie as yet nonexistent) magical web of trust that somehow doesn't destroy your privacy in the process of being used. (It's not as crazy as it sounds - we already have zero knowledge proofs, blinded encryption, and various other privacy preserving cryptographic schemes.)