WordPress has just announced that its blog URLs can now be used as OpenID usernames. This means that you are able to use your blog URL to log in to or create accounts with sites that are OpenID-enabled. The idea is that, ultimately, you will be able to log in to all your web-based services using a single OpenID identifier, rather than the multitude of various usernames and passwords that are currently necessary (at a guess, I would say that I have at least 10 different web accounts, all with different usernames and passwords).
Read/WriteWeb has a discussion of the OpenID project and the implications of WordPress’s announcement here, noting that while our WordPress blog URL can be used as an OpenID username elsewhere, you still cannot use an OpenID verifier to log in to WordPress itself. It would seem that, while ease of accessibility is deemed useful up to a point, it is more useful for some sites than for others.