According to this article, Brett Favre has turned down the chance to come out of retirement (again) and play for the Minnesota Vikings. He is quoted as referring to this decision as the hardest one he's ever made.
That's quite a string of hardest decisions: to retire from the Packers, to play for the Jets, to retire from the Jets...
I don't feel bad for him. I used it all up here and here when I was so moved by his first decision to retire.
Word of advice to the Vikings: Read my previous post. Don't gamble on Vick!