iOS 4.0.1 includes the signal bar changes to fix incorrect display of signal strength.
According to Apple, it will provide users a much better indication of the reception that they are getting in a given area.
According to the release notes, iOS 4.0.1 includes the following bug fix and improvements:
Improves the formula to determine how many bars of signal strength to display
Please note that iOS 4.0.1 won’t fix the reception problem, it will show the signal strength correctly.
Let me explain. Here are some key points from Apple's open letter to iPhone 4 users:
Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength. For example, we sometimes display 4 bars when we should be displaying as few as 2 bars. Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don’t know it because we are erroneously displaying 4 or 5 bars. Their big drop in bars is because their high bars were never real in the first place.
The real signal strength remains the same, but the iPhone’s bars will report it far more accurately, providing users a much better indication of the reception they will get in a given area. We are also making bars 1, 2 and 3 a bit taller so they will be easier to see.
So to summarize Apple's statement on the issue, if you’ve observed the reception issue then it doesn’t mean Apple will fix the reception issues as Apple can’t fix it as it depends on the your carriers network. The iPhone Software update will ensure that the signal is being reported correctly to give a much better indication of the reception that you’re getting (so that you can blame the carrier for the poor reception instead of Apple).
According to Apple:
gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones.
So you will still notice a drop in reception when you grip iPhone but it won't be as dramatic as it was observed in iOS 4.0. Ever since iPhone 4 was released, users seem to have forgotten that AT&T has a patchy network, iOS 4.0.1 should bring back the bad memories.
If you have jailbroken and/or unlocked your iPhone then it would be prudent to wait for iPhone Dev Team to provide an update on how the latest iPhone OS impacts a jailbroken/unlocked iPhone as you could end up bricking your iPhone.
But if you don’t care about jailbreaking or unlocking your iPhone then you can update your iPhone with iOS 4.0.1 via iTunes.
Apple has also released iOS 3.2.1 for iPad, which includes number of bug fixes and improvements including fix for Wi-Fi connectivity issues.
As always, please don't forget to tell us how it goes.