Johannes Ernst, whom I linked from my piece on InfoCard last week, wrote in to point out that I erred in my quick description of the service. He says that in InfoCard:
…the PC does not actually store the identity information, only pointers to it. The actual identity information is stored by identity providers, who are the “3rd party” in the system (the other ones being the relying party, such as a website, and the PC component).
This makes InfoCard much less like Apple’s Keychain (or for that matter the existing Windows saved password feature) and more like, well, a federated identity system. Interestingly, this is consistent with what I remember from the discussion of the future of Passport back in 2001 with MSN execs.