I'm not one for conspiracy theories, but I think that there is a lot more to the Packers, Favre story than meets the eye.
In my opinion the ball got rolling the moment that Ted Thompson chose Aaron Rogers with a first round draft choice. Favre has been in the league a long time and knows how General Managers operate.. how they don't feel that a team has their stamp on it unless they choose the player the team revolves around. I am confident about this because right away Favre made it clear that he wasn't there to mentor Rogers.
This feels a lot like what the Chargers went through with A.J. Smith and Drew Brees (except Brees wasn't a legend). While Smith took part in drafting Brees while working under John Butler, he didn't pick him on his own. He did however pick..rather trade for.. Philip Rivers. Even though Brees beat out Rivers for the starting job and proved to be a high quality starter Smith picked Rivers and that is who he wanted to be the starting QB of his team, so Brees was shown the door.
I have to beleive that the only reason you would get rid of the man who had you within one play of the Super Bowl only to replace him with a kid that has never started an NFL game (in fact no QB on the roster has started an NFL game) is because your ego is so big it rivals Mt. Rushmore.
Favre hasn't come out and directly said so, but you can read between the lines and see that he feels that he has been pressured to step aside for the last several years. Thompson could not just come out and tell Favre to step aside, the fans would have ran him out of town. So how do you get rid of a player of his stature? By doing subtle things to get under his skin and make him want to retire (i.e. not picking up Moss for pennies on the dollar).
I for one like the way Favre didn't go out quietly. Thompson was hoping to come out of this smelling like a rose and while Favre isn't exactly aromatic coming out of this, at least he ousted the man responsible for parting a beloved legend from the town that adores him.