Google Showing Facebook Friends On Profile URLs

Google Blogoscoped reported that Google seems to be testing showing Facebook friends in the Google search results for some Facebook profile URLs. For example, a search for facebook marissa mayer, I see the following search snippet:

Why is this showing up? As Philip notes, it doesn’t seem like Facebook is using the rich snippets markup for Google to show this richer snippet data. In fact, I doubt Facebook would want to give Google more of their data, to expose in the public Google search database.

This does appear to be very similar to how Google showed dates and forum thread details in the search results as well as the early on reviews.