Google has added a number of new social calendars to the options on Google Calender, the most notable for geeks being your friends' birthdays. Dates are pulled from your GMail contacts that have filled in their birthdays in their Google Profiles.

This could be a fascinating example of using multiple services together in a way that adds value to users' social lives and incentivizes them to contribute personal data to the system. It would be if anyone but geek early adopters filled out Google Profiles. Give it a try, though, and let us know whose birthdays appear for you. Old friends and family? Or just geeks online? More.........