While Steve Jobs gave no clear indication of how Apple plans on taking care of hardware aspects of the antenna(gate?) problem, with iPhone 4. He played really smart by offering anyone with an iPhone 4, to apply for a free case in order to get rid of falling 3G signals.

And just in case that does not work for you, you can still return an 'undamaged' iPhone 4 back to Apple and get a full refund within 30 days of return of the item.