Yes, I've been wondering about this one since I heard about it earlier this afternoon. I really don't understand this move by the Chargers. Junior was one of the players that should finish his career with one team (of course, that list also includes, among others, Emmitt Smith, Joe Montana and Jerry Rice). I know Seau has had a little more injury affect his play of recent, but I still believe he is the heart of that defense. If San Diego wants to go anywhere next year, this is not a good move, IMO.
I'm sure Seau wanted out. He is on the last leg of his career, and he wants a shot at winning the Super Bowl. He does not have time to be part of a rebuilding process. I'm guessing that he demanded to be traded, and the Chargers, out of respect and a desire to build for the future, decided that it "was the best for both sides."
Junior would be welcome in Seattle with open arms, especially since it looks like we won't be getting Hugh Douglas.
They also got rid of Rodney Harrison, who was as much the heart and soul of the defense as Seau was. I'm from SD and a Charger fan, and I actually think this wasn't too bad of a move. I think the future of the team lies more with guys like Quentin Jammer and Donnie Edwards. There might also be nefarious things going on with the Chargers trying to leave town, but that's another topic.