Manny being Manny is great.. when he's actually producing, but he hasn't been the Manny of old for a while now. He isn't getting any younger, and I don't think that he is the token veteran that team needs.
Probably not happening given that Adam Lind probably isn't ready to play first base every day. Also, getting Manny right now has vague echoes of the Jays signing Frank Thomas in 2007 and thus totally robbing themselves of lineup maneuverability by having to lock the Hurt into the DH spot every day.
There's no downside to this move for Los Angeles, who were going to go after a free-agent pitcher of Haren's caliber in the offseason anyway. And they didn't give up much at all to get him from the D'Backs, who I agree are rudderless right now.