Distributed identity management

Contact and address book management is annoying and over manual - this should be automatable. Here are a few cases that highlight the redundancy and time wasting right now:

• Mike changes his phone number. Mike either hopes people notice the change or he emails out his new number to people he thinks have his old number. Wouldn't it be better if wherever you had Mike's number, it automatically became the new number?
• Jane wants to use Facebook as her address book. But there's no way for Jane to add a phone number to a contact such that only Jane can see it. Even more difficult - Jane's grandmother isn't on Facebook. Jane can't create an address book entry for her grandmother.

I don't know exactly what the proper solution is, but I'd love to see some kind of distributed e-identity system that allows for notification of changes with minimal interaction. I see it working somewhat as following:

• I have a list of contacts. For some contacts, it's information they curate. For others, it's information I enter - maybe they've never participated online in this system before.
• I can see who's got me listed as a contact. (Or I can see who's listed me as a contact and opted into me seeing that they've listed me)
• When I change some detail about myself, I can select whom I'd like to notify about this.
• When users get notifications about a change (maybe email), they can choose to accept or ignore the changes. Or if a user doesn't act on it immediately, the information is annotated with the change and the user can accept it or reject it later.
• I can choose to trust people's changes - I don't even see their update notification, their contact info is gracefully changed.

Some solutions get close - most notably Plaxo. Plaxo charges $60 a year for the sync, though, and I don't think an external service is necessary for this. Address Book's use of vCards allows me to send out a vCard when I change my information, but vCard doesn't seem seamlessly integrated into other services and isn't as graceful as I'd like.

I'd love to see better integration across different services and applications on this. I'd love to see my Google Contacts knowing about people's Facebook information. I'd love to see this taken from an occasional sync to a gracefully pervasive and integrated system.