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.
So if you bought or buy your iPhone 4 on or before September 30, and you just want a free case, download the Apple case program app and order it asap.
If you get your iPhone 4 on or after October 1 and have a real death grip or death touch problem, you'll have to talk to Apple Care for your free case.
[Apple.com, thanks to everyone who sent this in.]