Can Internet SSO Really Help?

What does Internet Single Sign-On systems really solve? Is all this upset (caused especially by OpenID) good for anything? Let's summarize the benefits and drawbacks:

My assessment is that Web SSO systems that just do SSO are useless. Absolutely useless. Dangerous even. I think that for this stuff to work reliably and securely the browser needs to understand the security protocols. The browser needs to present appropriate user interface, such interface that cannot be feinted by a script. And most of all: the SSO itself is a next-to-none benefit for users. Add attributes to that and it may gain some attractiveness.

Do not take this as an endorsement of CardSpace. While CardSpace may solve some of the above issues, it has its own set of problems. But I will keep that for later.