As expected, Apple has reevaluated their iPhone case initiative: "We are discontinuing the free case program on all iPhone 4s sold after September 30, 2010." But they'll still give you one if you complain.
The text on the iPhone 4 Case Program page reads:
We now know that the iPhone 4 antenna attenuation issue is even smaller than we originally thought. A small percentage of iPhone 4 users need a case, and we want to continue providing them a Bumper case for free. For everyone else, we are discontinuing the free case program on all iPhone 4s sold after September 30, 2010. We are also returning to our normal returns policy for all iPhone 4s sold after September 30. Users experiencing antenna issues should call AppleCare to request a free Bumper case.
Of course, if they thought their antenna design flaw was so small, why give free bumpers to everyone at all? And why keep giving them to those who ask for it?