While I don't like Michael Vick, started the other sited thread and feel in my heart that his is guilty as charged, I do believe in due process and our system where a person is innocent until proven guilty. For that reason, I wouldn't sign a petition at this time. Personally, I don't think petitions do any good except in very extreme circumstances but that's another story.
If Michael Vick is found guilty, his NFL days are over anyway and his contracts with Nike and others are history. Even if he is acquited, I'm not sure he will play again anyway. There are still going to be owners that won't want to be associated with him and players that won't want to play with him. Most teams wouldn't want the distraction that he would present. And last but not least, he is the most over-rated player in the NFL. He is a terrible quarterback that has a good set of legs that help him get by.