I don't know about your experiences, but I've been having a lot of trouble using OpenID on different sites.
I was just on the new Open Web Foundation site (more later on that) and you'd expect MovableType software to actually work with OpenID properly. Well it didn't, and not for lack of my trying.
I think OpenID solves a problem that must be solved, but it probably needs to be a little simpler to implement if it's going to be heavily used (as it should).
Speaking of OpenID, one of the questions we get a lot when we explain .tel is "can I use .tel instead of OpenID?"
In other words, people wonder if it might be possible to use .tel for identity authentication upon launch of the TLD.
The short answer is: no, the purpose of .tel is not to authenticate your identity.
The longish answer is that .tel puts you in control of your communications and allows you to centrally manage and securely publish all your means of communications. OpenID solves a totally different problem, which is cross-site authentication, otherwise called "single sign-on".
You can of course publish inside your .tel your OpenID authentication URL, making it easy for applications to discover that you own an OpenID. That's something I'd like to pursue at some point, so that in replacement to having to enter my "http://openid.aol.com/username" in the OpenID authentication field, I could simply write "henri.tel" and the website would pick up my OpenID url (assuming I want to have it public) from henri.tel. I can also encrypt my OpenID url on henri.tel, but then I'd have to give the website proper friending status to see it, which would make the system more complex. But having more options is always good. :)