We are not sure yet
Fruity peddler of broken iDreams, Apple claims to have fixed faults in the iPhone 4 which include sluggish performance to unreliable proximity sensors. Apple insists that the problem has not been caused by poor design and shonky hardware.
It claims that the fault lies with version 4.0 of the operating system, which came pre-installed in the iPhone 4. It faces problems ranging from a sharp dip in the performance of the iPhone 3G to a failure in the proximity sensors in the iPhone 4 which caused phone calls to terminate suddenly while the user was talking.
Apple Grand Pooh Bah Steve Jobs said that the iOS 4.1 would soon be released this week to fix the iPhone 4 proximity sensor problems, sluggish iPhone 3G performance, and some Bluetooth connectivity issues. According to the Mac press there are signs that the proximity problem has been fixed.
The iPhone 3G performance problems have also been fixed according to Apple's own user forum. At the moment that is all we have seen from the tame Apple press. It will be a few days before users can tell if the corrections are a placebo or not.