At the Boston Comicon, currently underway, I understand that DC Comics Co-Publisher Dan DiDio has been heard telling retailers that orders on the September "Villain's Month" titles have been allocated up to 40% in some cases.
For the month of September, DC are publishing a new style of 3D cover for every one of the Villain's Month titles, in which all the comics are renamed and renumbered to give villains a new #1. However, due to the length of production process, the orders for the covers had to be set well before the usual FOC date, and DC Senior VP – Sales, Bob Wayne talked at San Diego Comic Con about having to make his best guesses for setting the print runs early.
But it seems that in some cases that might have underestimated retailer demand considerable, with some titles only filling 60% of their expected orders.
DiDio has reportedly talked about filling the void with non-3D covers.