It’s indeed a custom font created by a designer called Joe Kral
(‘Klavika Bold’ is accepted as the closest font you can get):
Editado el 29/01/2013 a las 01:41 por rocamaco
It is a custom font, indeed. Klavika is close, but the font Facebook Letter Faces is based on the logo, so I think that is the best one.
Huso horario CEST. Ahora son las 07:50