Artest's foul was *NOT* a "normal foul." A push from behind when a player is in motion is DANGEROUS. Whether or not the foul was called a flagrant, there's no doubt in my mind that it SHOULD HAVE BEEN.
I have not seen Wallace's foul on Artest, however, if Artest had a problem with it, he should have done what Wallace did a play later. While I don't like to condone violence, even I recognize that there's a fine line that is walked in sporting events when officials don't appropriately make calls. Like it or not, responses to flagrant fouls are a part of the game. The smartest understand when to walk away - like Garnett did with Anthony Peeler last year. But if you believe Peeler won't catch an elbow from Garnett during this season if the opportunity presents itself, you're kidding yourself.