Moxie Marlinspike and Trevor Perrin have submitted a proposal to the Internet Engineering Task Force (IETF). The draft document describes a new way of server certificate validation based on the trust accumulated and shared by multiple clients. The proposed TLS protocol extension is called Trust Assertions for Certificate Keys (TACK) and based on public key cryptography, however, it does not use the Public Key Infrastructure (certificates and certificate authorities).
The text of the proposal:
The article in InfoSecurity magazine: