Well, it turns out he really is retiring after all.
What is really interesting in that article is what Chris Mortensen says at the end:
Mortensen reported that Favre, who wanted the Packers to obtain Randy Moss when he was a free agent last season, had once again pushed for Moss to join the Packers. Favre had spoken to Moss late last week and was willing to commit to more than just this season if Moss and the Packers could come to an agreement. But the Packers did not pursue Moss, who re-signed with the Patriots on Monday.
Update: Mort went on about the importance of not getting Moss with Favre's retirement on "First Take", saying that Brett essentially made the decision right when Moss signed with the Pats. Well, Favre did not like Mort saying this, claiming it was not the main reason he retired last night. He just called Mort minutes after that report, and left a lengthy voicemail to clear up why he really retired last night, and Moss was not a major reason for it. Odd.