It is literally a Moleskine Facebook, filled with quick portraits. Rob Wittig shares the artist's preference for the notebook in this post at 24-07 Design Heaven:
"Count me as another guy who has a weakness for the rounded corners, the elastic strap and, above all, the warm ivory of the Moleskine sketchbooks. Not always . . . I like a clinical white background for drawings, too. But Mole puts together a juicy package, I must say.
One of the best uses of a Mole I've seen lately is this nicely named online exhibit by illustrator Joseph Daniel Fiedler at drawger.com: the Moleskine Facebook."