Notice Lance with the yellow/black helmet
Lance grabbing the guy's shoulder. Since the guy is running his spandex ass off on the edge of the road, covered in snow, his balance has got to be sub par. Notice that he has his cell phone clenched in his other hand.
Lance tosses him into the ditch like the prissy boy he is (I would suspect he goes by the name "anonymous"). The fall must have been hilarious to watch since he had his prop in one hand and his phone in the other. Lance is not in this picture because he is behind the Astana ride with the blue arm warmers. You can see Chris Horner (Astana) laughing a few riders back and a guy from Saxo (in white jersey at end of pic) laughing as well.
This picture is pretty tame since this could have resulted in a crash since he sluffed so much snow on to the road from the bank. But I would imagine that if he were to have caused a riders to go down, the subsequent pummeling that he would have received would have added to another great series of photos.