I, too, was looking at the 135mm yesterday on Amazon for $879, and today it's $989. I see that this matches B&H's price, which shows the rebate of $100 from the $1089 price.
I guess I'm a little confused... I get the idea behind MAP, but why were these cheaper yesterday? Did Amazon and B&H have them marked down, AND the lens rebate applied???
And couldn't these stores still offer them for the same price as yesterday, but hide the price, and only have it available at checkout, or virtual carts, or whatever they do to get around the MAP law in effect?