I think that so long as we leave content on other people’s sites (or in their in-boxes) we will have the dual problems of spam and host lock-in.
The primary use of OpenID should not simply be identification, but also, to tell remote sites where to direct our actions. So – in a sense – I carry all my own home website tools with me when I travel around the web.
(Reading this in an RSS reader? Here’s a direct link.)