Let us start by looking at the issue of chucking not from the cricketing definition but from a batsmen's viewpoint. Let us take the issue of chucking from three different types of bowlers: the fast bowler (like Shoaib Akhtar or Brett Lee), medium pacer (like Shabbir Ahmad) and spinner (Muthiah Muralitharan/Harbhajan Singh/Shahid Afridi).
Let us all assume that all the three different types of bowlers are blatantly chucking (with a bent elbow and literally throwing at the wicket, baseball style). Let us also assume that the pitch, the condition of the ground and ball (all these might or might not help the bowlers) all favour the bowlers.
We see immediately that the batsman is going to have a torrid time against the fast bowlers and a little less or equally torrid time against the medium pacers and a relatively easier time against the spinners. This is because there is more time for the batsman to react to the spinners than the pace bowlers both fast and medium. And this is just common sense. And when we are talking about batsmen playing international cricket as of now, they are all accustomed to the quicker ball and we therefore assume they would have an easier time against the slower bowlers.
I think it is safe to assume that whenever a bowler is chucking, he is trying to use his bent elbow to a maximum benefit by throwing at the stumps with the maximum speed. But when we come to spin bowlers, the whole idea of chucking is ridiculous as there is no speed that is threatening the batsmen. Yes, there is the case of turn. But to me, when I try to turn the ball, pace is not what comes to mind; the more turn I want to generate, the slower the ball should be (as it has go through the air more to jump of the pitch). And what's more, it becomes exceedingly difficult for anyone to throw and turn the ball at the same time. If you don't believe me, try it out yourself.
When it comes to Murali, right from the time he made his debut in 1992/1993 till the recently-concluded match against Australia, most of his career has been surrounded by controversy regarding the legality of the action. And we all know his ability to spin the ball almost square even on a concrete pitch is what amazes everybody and makes him almost unplayable. Hence, the assumption that he is chucking!
The controversy about his action has always coincided with whenever Sri Lanka plays against Australia or England, both countries not the best players of spin.
I think the reason why Murali is able get much turn is because he releases the ball from the back of his hand. His bent elbow enables him to get additional spin. Try spinning the ball with your fingers (off-spin) and try releasing the ball from the back of your hand and you will see the difference.
Australians, as we all know, are not the most scrupulous of the lot when it comes to playing cricket (who was the last player to have walked before Adam Gilchrist's one-off incident in the World Cup match against Sri Lanka?). The English, who are not the best players of spin, have just decided to give Murali a hard time just because they can.
I think the whole point of chucking becomes an issue only with speed. The faster you bowl, the more stringent the rules of chucking should be. Bowlers like Brett Lee and Shoaib Akhtar chuck more, and more blatantly, but nothing is done about their action. (Check Lee's chucking at Perth and Shoaib's chucking all through the recently-concluded matches against India).
Let the ICC focus on the bowlers of fast and medium pace and let the speed gun be used in tandem with the ICC rules for chucking. If you can't play a ball at 70-80 kmph, you better not play international cricket. Let us all leave Muralitharan do his job in peace. If you cannot move your feet and hit the ball, train harder; don't hide behind the ICC's impotent chucking rules.