Perjury charges from his testimony in front of congress. Pretty much it will be proven either Clemens is clean (never used PEDs) or that MacNamee is right and Clemens used - and then lied about it to congress.
Formerly (and other baseball fans) I'd love to hear your take on this. I don't know how I feel about the general feeling on steroids. I feel like people who admitted wrongdoing (think Pettite) were given complete reprieve and Standing Ovations, while people who deny it (Bonds, Clemens), especially those who are assholes in general (bonds, clemens) are made villains.