For certain, OpenID isn't the first attempt at single sign-on for the Web. Recall AOL's early attempts, as well as Microsoft Passport, which is now Windows Live ID? I've used Windows Live ID, primarily because Microsoft Money has made it brutal to use the software without it. Even a company with the clout of Microsoft hasn't been able to successfully push SSO to the mainstream in a significant way.
And, considering Yahoo started the SSO idea in 1994, and Microsoft followed suite with MSN Passport in 1998, one can't say they've exactly taken off. And I doubt OpenID will get much past the early adopter crowd.
Don't get me wrong, I'm as tired of managing passwords as anyone. In fact, it's getting ridiculous. Currently, I've more than 200 username and password combinations I need to manage. The only way to do this is with a robust password manager. I use Siber Systems' RoboForm for Windows, which is also an excellent password generator and Web form filler. Ditto for Agile Web Solutions' 1Password for OS X.
For now, these applications handily beat all of the current vendor attempts at Web-based SSO. And I suspect that's the way it's going to stay for some time to come.
So while Yahoo is a great boost for OpenID, this platform isn't going to fly until we start to see big banks, credit card companies, and many more businesses get on board.