Two-factor authentication

I think this is a reference to the fact that Yubikey's model is event-based one-time passwords, as with HOTP which it does support as an option. These comments include a response from the vendor explaining more and linking to a third party security analysis: http://www.mnxsolutions.com/security/secure-ssh-and-wordp... - the article talks about using Yubikey to secure SSH and WordPress logins.