A test conducted by Adrian Kingley-Hughes at ZDNet appears to prove that the battery-draining issue that is affecting some iPhone 4 and 4S owners doesn't have it's root in hardware. Using a pair of identical, purchased-on-the-same-day iPhone 4S handsets, Hughes and his developer tester were able to make the battery issue "jump" from a handset that had the problem to one that didn't by swapping backups.
