Yesterday evening, Google announced the launch of their Contact API. This is ultimately part of Google’s plan to “out open” Facebook. This is an amazing first step. You finally get to own your contact data and take it with you anywhere. Users have the ability to add, remove and modify existing contact data. The only step left is for Google to enable you to describe each of your relationships in a categorical manner similar to the new custom friend grouping feature (friends lists) on Facebook.
This will enable users to select default privacy settings for each group when they register for a new site.