On the EnThinnai Blog, and highly recommended.

In particular, I like his analogy with credit cards. Coincidentally I have been using the same analogy for some time, although not in public so far.

While in case of OpenID the currency obviously isn't money, the two systems are remarkably similar in many ways.

They differ in case of maximum possible disaster. In case of a credit card, the maximum loss may be high but is "only" money, which can be restored through liability or insurance. In case of OpenID it it privacy, which for some data (like health information) cannot be restored.

But it is time for businesses to think of accepting OpenIDs in the same way: just like credit cards let you "outsource" credit evaluation, in case of OpenID you can outsource identity verification to providers like AOL, Orange, and hopefully others, who offer this, amazingly, to you for free! Even a better deal than credit cards where you have to pay a commission!

So the bottom line for businesses is: OpenID saves you money, because you don't have to do something (identity verification) that you otherwise have to do yourself.