This is not gimp’d or photoshopped after the fact — Comedy Central actually flashed it (for one frame only!) over Stephen Colbert’s face as he interviewed Salon.com journalist Glenn Greenwald about Anonymous [1], the inchoate online group that, among other things, attacks those who attack Wikileaks.
Got all that? Good.
My friend Micah Anderson has sharp eyes: he spotted this as he and Biella Coleman and I were watching the episode in real time, and later he went back to do a screen capture:
Or was it Anonymous themselves, tweaking Colbert? We may never know…
It helps to know that the Guy Fawkes mask is one of their symbols: