Google's social applications that will be included should be: Gmail, Calendar, Docs, orkut and probably others. orkut has recently launched a feature that aggregates and displays all the updates from your friends, so the new feature will be similar.
The updates from your friends section on your homepage shows updates when your friends perform the following actions on orkut:
* make changes to their profile
* make changes to their photo album
* make changes to their video favorites
* accept new testimonials
When you make these changes to your own profile, your friends will see your updates on their homepages.
The new project could also mean a radically improved contact manager that shows a lot of live data from your contacts. Hopefully, the data will be searchable and only available to the persons you trust.
Note: Most of the information from this post comes from a confidential tech talk in which Google's Ben Darnell explained to some Nooglers (new Google employees) how Google Reader works. This tech talk is part of the "Nooglers and the PDB" series of weekly talks, which is open to all Googlers, but it was accidentally posted on Google Video.
{ via Blogoscoped. Screenshot licensed as Creative Commons by Danny Sullivan. }