OpenID is good technology. And it seems to be gaining momentum.
OpenID solves the problem of you having hundreds usernames and passwords all over the Web. Instead you have a single identity that lets you log into all participating sites. It's convenient for both users and websites.
A key feature of OpenID is it's decentralized. No one company owns all OpenID accounts; instead, users are free to choose their own OpenID provider (or several, for that matter). OpenID is like Passport without a predatory monopoly owning everything. Or like the Liberty Alliance without the miasma of failure.
OpenID was originally designed as a quick hack by the brilliant Brad Fitzpatrick. It's had a lot of iteration and design and now it's picking up momentum. There's signs of support from AOL and Microsoft. And lots of little guys. There's even third party support for Yahoo accounts. All that's missing is Google.
The politics here are interesting. AOL, Yahoo, Microsoft, Google; they all want to be the sole owner of user accounts. Maybe they're figuring out that will never happen and that the next best thing is to be the OpenID provider for the most users. The real beneficiary are small web sites. I'm much more inclined to try out a new service if it doesn't require creating yet another username, password, and waiting for an authentication email to traverse my spam gauntlet.