If not, here's the quick version. His players traded autographs and memorobilia for benefits like tattoos and such, and he claimed he didn't know about it. Then it came to light that he did know about it. As the investigation continues, it looks worse and worse for him. And he lied about it, which the NCAA hates.
But anyways...everyone that follows college football at all knows who Tressel is, and they also know that he goes to EVERY game with a Buckeye red vest on...which makes this billboard between Ann Arbor and Detroit (near the University of Michigan campus) hilarious.
Clearly it was put up by someone (or some group) of fans or alumni from Michigan, who is Ohio State's rival in just about everything.
I thought it was pretty amusing.