re: Breaking Bad Thread (NO SPOILERS OUTSIDE OF THIS THREAD. INCLUDING SIGS & CHATBOX.)
Walt's ego has taken him over, the cackling laughter when he found out that Skyler had given his money to Ted was the tipping point for him IMO and that laughter returned when he lied about Gus poisoning Brock, which is Walt's most abhorrent act thus far. I wouldn't say he's beyond repair, and I could see some sort of redeeming suicide/self sacrifice ending with him, when he realises that he's completely out of control. It's still been obvious throughout that he cares about his family and Jesse, who he has a father/son like relationship with.
The fact that all of the characters are so complex is amazing. They've been so well developed, it's been an incredible job by both the writers and the actors. If Jesse gets killed off it will hurt.