(And btw a cool and stable OpenID server would be good also…)

for that, there’s delegation. You can have your own URI (for example, your website or blog) in which you specify (in link elements inside the head of the document) your active provider. You can then switch to other providers and keep the same identity URI everywhere. (click my name for an example)

For less savvy users, the consumers should allow more than one provider URI attached to each account. Ma.gnolia allows me to attach several OpenIDs to the same account, which is great.

If I understand OpenID correctly, isn’t your identity a URI? So if you switched providers, your identity would change because your URI would change.