Jackson Shaw provided a great use-case for claims-based authorization this week. While I've always seen the value of the claims-based approach, I've always felt that the thing that's missing is the motivation. End-users and consumers are typically motivated by what is easier or cheaper. Corporations, similarly, are motivated financially and not, as we might hope, by security or privacy as an end in itself. But his example, which applies to any major corporation who gives discounts based on employer (hotels, car rentals, wireless phones, etc.) shows that there are millions of dollars on the line.
$$$ = motivation
It might be just what corporations need to push them toward adoption -- and that includes providing incentives for customers to move to a claims-based model. I think mobile phone companies are situated perfectly - they can provide the authentication mechanism built into the devices they sell, which makes it potentially easier for users to browse the web (could solve the 'numerous passwords' problem) - remember:
Easier = motivation
...and they have a huge financial motivator because many big companies negotiate mobile plan discounts for employees.
But perhaps budgets can be pooled together by a consortium of companies that are losing money to create a compelling solution that end-users will want to adopt. And in the end, we'll see better security and privacy as a result.