If you purchase an iPhone 4 before September 30, 2010, you are eligible to receive an iPhone 4 Bumper or a select third-party case from Apple at no charge. To get an iPhone 4 Bumper or case at no charge follow these steps:

For iPhone 4 purchases made before July 23, 2010, you must apply no later than August 22, 2010; otherwise, you must apply within 30 days of your iPhone 4 purchase. To qualify for this program, you must purchase your iPhone 4 by September 30, 2010.

Also Apple will give you a full refund for your previously purchased iPhone 4 Bumper, including any taxes and shipping fees. Just fill out this rebate coupon and mail it to Apple by September 30, 2010. You can get more information about the Case Program on Apple’s website.