The Radar team has a good post up about the pros and cons of OpenID.
So what does all that mean?
It means that there are a lot of people who have OpenID, but they don't have many places to use them and they probably aren't aware that they have one. It is a good step towards solving some key online identity problems through an open standard that isn't trying to solve every problem at once and is instead focusing on deployment and handling issues and requirements as they arise organically. We are overall bullish on OpenID, but the security and usability issues need to be addressed before there is wide-spread user uptake and the larger players become acceptors.
We've also found the sign-in and registration to be jarring and confusing to users, but that will undoubtedly improve as partners open up (and improve) affiliate programs.
As I said before, OpenID does not define the mode of authentication, only the link between the authority and requesting site. In that sense, there's no reason someone can't provide a keyfob-based authentication site for banking and healthcare sites.