Just found this: The german website Radsport-news.com says that Greipel has injured his shoulder in that early crash, but is continuing on.
edit: Earlier in the stage, Lotto leader Greipel had crashed. His teammate Francis de Greefe, the two Spaniards José Ivan Gutierrez und Alejandro Valverde (both Movistar), Dutchman Robert Gesink (Rabobank), Lieuwe Westra and Kris Boeckmans (both Vacansoleil-DCM) also went down.
Valverde had some treatment at the race doctor's car after that, but we don't know the extent of the injuries. All riders continued the race.