Yahoo! announced that it was implementing a new feature in its web-based mail client that automatically updates your contacts' most up-to-date email addresses, phone numbers and home addresses.
Yahoo!'s auto-updating "Share my info" feature changes address books to a subscription model where consumers constantly share their most up-to-date contact information with their friends and contacts.
It's a much more effective way of keeping in touch with friends that travel, or those who change their phone numbers every week and are constantly being kicked out of their apartments.
In many ways it is similar to Facebook's contact information model. When one of your friends changes their contact information on Facebook, the social network sends you a message notifying you of the change.
For more information about how to activate the service on your Yahoo! mail account check out Yahoo!'s March 18 Mail Blog post here: http://www.ymailblog.com/blog/2010/03/a-yahoo-contacts-that-updates-itself/