INQ says they got Facebook to extend their social graph API and then are using behind-the-scenes wizardry to suggest top 5/10/20 friends you interact most with.

INQ说他们可以利用Facebook来扩展他们的社交图谱，然后利用这些背后的关系推出前5/10/20个最常联系的朋友。

youdao

In my last post, I defined Right Time Experiences as experiences that are derived by analyzing and combining contextual data from mobile (such as location, motion, prior usage behaviors) with data from your social graph and with data from the cloud that may be accessible via an API (e.g. weather, available parking in a area, restaurant table availability).

FORBES: Is Mobile Dead or Entering a New BattleGround?