Yeah, a lot depends on whether the person who leaked the information had any sort of legal duty to the players, by contract or because of some special relationship. I'm pretty sure it's a government source, the government having gotten a hold of the list legally. Maybe there's some sort of way to recover against government employees who leak information obtained in a police raid or something; I have no idea.
Practically speaking, though, any lawsuit would be an admission by the players that they were doping. Players who we already know did it would look like bigger douches for suing people for telling the truth, even if there was some legal wrong against them. And players who we don't know did it can't sue if their information hasn't leaked. So basically, they're all fucked.