Good luck on getting users to actually do public key encryption. As
far as I can tell, unless an app builds it in behind the scene, only
very technical people ever generate a key pair and know what to do
with the parts.
Justin Gehtland gave a good talk at RubyConf on Rails authentication
that covered OpenID and alternatives. All the talks were videoed by
Confreaks and will be up on the web soon, in a doublewide format that
shows both the slides and presenters. Judging by the blogging of
release times from previous conferences (MountainWest and Hoedown),
I'd guess the presentation videos will start appearing in a week or two.