For those who didn't see the recent kerfuffle: This guy recently found and demonstrated a major Rails exploit on github. He seems to know a thing or two about security exploits.
Clarification: he didn't recently find the exploit. He's been making noises about it for a very long time and being ignored, so he took the (dubious, to some) step of using the exploit publicly and loudly, to draw attention to the problem.
Point, dood.