Apple:

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.

This is no surprise. Shortly after Apple announced the free case program in July, talk of actual problems associated with the attenuation practically disappeared. As expected, the antenna problem wasn’t as big of a deal as it appeared to be.