iGoogle, Google's personalized homepage is on its way to becoming a of social network thanks to their just announced adoption of the OpenSocial API. In particular, the just launched developer sandbox will allow gadgets on iGoogle will be able to access friends' data and to create "activity streams" (akin to the Facebook news feed). Shown below is the Updates Gadget where using the OpenSocial API "you can post updates to the updates gadget. Users will be able to see updates generated from their friends' gadgets, encouraging content sharing."
As this is in 'sandbox' mode, this feature set is available only to developers and is not yet rolled-out to the general iGoogle population.