This is the Lebron rule. The amount of times I've seen him catch the ball on a break, take 2 strides and THEN put the ball on the floor is ridiculous.
It will keep the game moving quicker though and big men will be able to get closer to the basket for a big finish off a short pass inside the arc.
Interesting to see how it translates into FIBA games. The NBA has had it's influence already on FIBA however, by demanding the arc be brought out 2 feet approx.