Combined with rumors that the NSA knew about Heartbleed, this makes me wonder if they actually were involved in outing Silk Road. As far as I know, we still haven't seen any indication on how the FBI managed to find and image the Silk Road server.
I would be shocked if they weren't involved in outing Silk Road, in some sort of multiagency effort. It's not clear NSA couldn't de-anonymize specific TOR services if they wanted to even before we knew about Heartbleed though.
Large-scale traffic analysis (dragnet surveillance) + hacking into exit nodes already made compromising TOR users technically feasible before the heartbleed exploit.
The whole cypherpunk/online anonymity movement which spawned TOR was largely predicated on nation states acting legally. But when they can secretly hack into every router, fiber cable, and gateway endpoint without any question of legality then anonymity and privacy online is no longer an option for anyone, even the most technically-proficient.