tedster - 11:55 pm on Mar 24, 2013 (gmt 0)
I recently ran into the same thing. In the case where I saw it, it made some sense because the company involved was running a very active and interactive Facebook presence, but their regular website was kind of static and not recently updated.
I'm not sure having FB at #1 and the company site at #2 really makes sense for Google's end user, however - the query was pretty generic (and somewhat navigational). In fact I was looking for the actual company website at the time, and not their social media presence which I don't think would hold the kind of information I was looking for.