In this post on Cryptome it's noted that a person called Michael Vario is willy-nilly signing people's public key's and uploading those signatures. He is effectively forging a web of trust. I'm sure this kind of thing has been done before.
It occurred to me that if the public key servers could be asked to return public keys with only those signatures that are reciprocal we would perhaps have a more realistic picture of who trusts who. With this feature enabled Vario's signatures wouldn't appear in any of the keys that he's signed and his effort would be for naught.
Would this key server feature be useful?
Would we also need some additional options/messages in GnuPG to make it clear when you might be looking at an "unauthenticated" signature?