I have tested yubikey briefly, and altough it is an interesting technology, I found it unusable for my needs, because of two problems:
- central authority: I maintain several servers, and I want to be able to log in even in case the server is half-broken (i.e. DNS or network only partly functional). For an ordinary user, Yubikey is a great technology. For a server admin, not so much.
- multiseat: at home, I have a multiseat workstation, and I have so far not found an easy way how to configure to which head the hot-plugged keyboard (the yubikey module) should be mapped. I have primary keyboards for both seats configured statically in their respective ServerLayout sections in xorg.conf.