A cool screencast done by Simon Willison all about How to use OpenID. I've never heard of it before, but it sounds like an interesting way to do identity management. Of course, it needs more sites to become "big". The principle is similar to that of Six Apart's TypeKey service, just not tied to a single site.
From what I can see, OpenID is basically allows sites that "talk" the openID protocol to delegate identity management back to the site. So in theory I can set up arcterex.net to delegate as the authoritative domain for the ID alan.arcterex.net, same as livejournal delegates identities for "username".livejournal.com.
Never knew the capacity was there, potentially very cool and useful.
Now go forth and update your blogs!