Rated 5 out of 5 stars
I believe Web security is like within a submarine, it requires (how do you say in English, "compartimentage" ?) ... partitioning ?
This is why I will never ever concentrate whatever IDs, logins in an OpenID. Never. But it remains better to use OpenID with one very strong password than to not use it and have multiple plain crappy passwords, for sure.
5 stars nevertheless because my comment is in a way biased.
Multiple OpenID providers / user's choice
I agree that a site with third party login should allow multiple identity providers. Translated to OpenID: An OpenID consumer should allow its customers to associate multiple OpenIDs with one account. Some OP support strong authentication so we can get rid of passwords. This way we get a better web through user choice. Putting all eggs in one basket is usually not a good idea. If the identity provider fails then both users and service providers suffer. Multiple OpenIDs with strong authentication are the way to go!