Well, I was coming at it from a developer's point of view. Here's a user story:
1. I don't have an account with this site. They say that if I have an account with (any of these other OpenID-supporting sites), though, that that one would work instead. Neato, but I don't use any of those, so:
2. I'll click on the register link here. Ah, here's a registration page. It doesn't have the site's logo on it, but they said that would happen--they've outsourced this part.
3. Registered. They gave me a link, and said "just treat it as your username." OK; I'll try to remember it, then. "It'll also work on all those other sites we mentioned, and more every day." Neato again; I might check some of those out.
4. I'm back on the site I started at, and I've already been logged in. They got my nickname right and everything.
(days pass)
5. "You've been logged out of the site due to inactivity." Oh, well, what was my username again? That link thing? Oh, here it is in the autocomplete.
6. Hey, it didn't ask me for my password! What the heck? I'm just logged in all of the sudden. I guess that's good, then.
(weeks pass)
7. "You've been", "inactivity", blah blah blah. Autocomplete.
8. Oh, I'm back on that site that did the registration. They're asking me for my password. Makes sense--they're the only ones that I told that particular detail. Put that in...
9. Ah, I'm back on track and logged in again. Nice.