Absolutely agree. Their social graph is their most important asset. It's a goldmine for any service. For the most part, it is the best indication out there of who you are connected to. So many sites and services are using this 'trust' network to provide services that weren't capable before. An example is a travel site (forgot the name now) that allows you to see if friends of friends are staying over at a hostel on a certain date.

They somehow have to monetise this.