Well this should be in the ESPN forum, seeing as there is one already about this there..
Basically what happened was one of his QBs in 1991(I believe) was given about $10k from a booster. Tressel was kept in the dark about it, he did NOT know about it. Ray Isaacs(the QB) said that he always kept it from Tressel because he did not want Tressel to suffer because of it.
The booster was an employee of sorts of the universities, and that's why Isaacs was able to meet him.
The media has not done their research and has jumped to conclusions other than the facts. ESPN and "The Lantern" are both included in the groups that have not done their research regarding this matter, assuming Tressel is dirty.
BTW: This did not just come up recently. There was an NCAA investigation at the time regarding this. ESPN claims that the NCAA just took Tressel and the AD's word that nothing was happening and they didn't investigate themselves. Nothing was ever found at the time to be wrong.