The list of sites that accept OpenID doesn’t include Microsoft, Yahoo! or Google, you might notice, despite the fact that they provide IDs. That’s because they’ve just signed up to the movement as a ‘provider’, not a ‘relying party’. That’s a shame, because now that everyone probably has two or three OpenIDs, it’d be nice to have somewhere to use them.
The OpenID movement is a decentralised service that’s supposed to provide you with one login for every website. It doesn’t work quite as well as that in practice, but it’s a very noble concept, so Google gets a small round of applause for providing them. A far bigger round of applause would be gained if they supported it themselves.