Quite possibly the hardest Guitar Hero song has officially being "FCd."
The special honors go to Iamchris4life, for reaching this milestone.
Official thread at Score Hero
Interesting things to note: "One" is the only song on Guitar Hero 3 yet to be FC'd on Expert.
Through the Fire and Flames is also yet to be FC'd on Hard. :\
Edit: The video is now available for you to see here