I found this piece on Gmail to be good commentary, in and of itself.
Authority mapping! Very cool. We could create a whole 'nother blog on that premise alone.
Separating the metadata from the underlying data it describes has let Google initiate a conversation in which users effectively trade general personal data for access to services derived from the aggregated requests. This scoped contract between users and the cloud sidesteps most privacy and political concerns.
Of course, the data needn't necessarily be personal, in order to work.
But of greater interest - to me at least - check out that innocuous little microphone ... How soon before all our various network interfaces include a headset for talk/playback, de rigeur?