Two students (Dan Wendlandt, Ethan Jackson) from carnegie mellon university have developed a system to improve the security of host fingerprint based authentication, protocols that use this type of authentication are secure web traffic(https) and secure shell (ssh), the system is explained by thier site as such:
Perspectives is a new approach to help clients securely identify Internet servers in order to avoid “man-in-the-middle” attacks. Perspectives is simple and cheap compared to existing approaches because it automatically builds a robust database of network identities using lightweight network probing by “network notaries” located in multiple vantage points across the Internet.
They’ve developed so far an ssh client based on OpenSSH and an extension for Firefox 3.