While I hadn’t been following the story as much as I perhaps should’ve (I don’t do a good job of keeping up with the tabloids), it seems that Levi Johnston is busily making a full-time, public horse’s ass of himself.
If you want the full story of his antics, John Hawkins has a great PJM piece titled “Levi Johnston is Trash, Plain and Simple.”
And boy is he ever!

He’s utterly poisoned his relationship with the mother of his child and her family. He’s in talks to do full frontal nudity for Playgirl. In another few years, when Bristol and Levi’s son Tripp is in school, is he going to have someone thrusting pictures from Levi’s Playgirl spread in his face? Is Tripp going to be proud of the way his father earned his 15 minutes of fame? A “man” like Levi Johnston who sees nothing wrong with putting his own child through that for his own tawdry self-aggrandizement doesn’t deserve to truly be referred to as a man.

Well, who says he has to be a man? I mean, is a sex change completely out of the question?
(Just kidding, folks. I really should be taking these things more seriously.)
It’s obvious that no one would care about this pathetic kid were he not the father of Sarah Palin’s grandson.

So Levi can try to make a career out of spreading lies about the grandmother of his child if he likes. There’s very little anyone can do to stop him since it’s a he-said/she-said situation. Some people will even believe him. Malevolent sociopaths like Johnston often manage to fool people — at least for a little while. So let him mouth off about his huge secret on CBS. He’s probably talking with his agent right now trying to figure out what it is and the biggest media outlet he can get to cover it. That’s what snakes like Johnston do when they get a chance.

Naturally, the media is exploiting him because they hope it will hurt Sarah Palin. Because of his age and inexperience, he may well end up self-destructing with the money he’s sure to make, and because Sarah Palin is a human being, that would probably hurt her more than the ridiculous stories he’s peddling. Either way, the people who are using him for political ends (or just to make a buck) won’t care.
Not that Johnston’s MSM handlers would care, but my personal opinion is that those who would capitalize on someone’s personal destruction in the hope of causing more personal destruction are beneath contempt.
There’s part of me that actually feels sorry for Levi Johnston, but OTOH, I realize that at 19, he’s legally an adult, capable of signing contracts, and accepting adult responsibilities. However, I have seen what can happen when teenagers encounter fame and fortune, and it can be very ugly. He better hope that he is a sociopath as John Hawkins says he is, because if he isn’t — if he has any shred of conscience deep down in there — such feelings can need serious medication, and this would most likely take the form of self-medication, for which of course he’ll have plenty of money (at least, until he ceases to be of interest to the media).
In any case, I wouldn’t worry about his silly “revelations” and “secrets” hurting Sarah Palin. By now she’s as tough as nails, and she can handle it. Besides, ordinary people have compassion, and they are intelligent enough to understand that if this kid makes a huge, grotesque public spectacle of himself, it will largely be because the MSM simply wanted to use him to hurt Sarah Palin.
And they’ll remember.
So, I think that the destructive behavior of Levi Johnston, while it may very well destroy Levi Johnston, will not only fail to destroy Sarah Palin, it might have the opposite effect.
MORE: Calling him “a naive kid who got caught up in a whirlwind,” Ann Althouse says she is worried about Levi Johnston:

He’s surrounded by false friends who will soon have used up everything he had to give. What resources does he have to draw on as his fame spike plummets? We are talking about a boy who is still only 19 years old. God help him.

And not a very bright boy at that. (Not that being intelligent prevents people from getting into trouble.)