I've recently started to notice that my home button has been a little unresponsive. Sometimes a single click won't work at all and it takes a few tries to get it to quit an app. Sometimes two clicks does what one click is supposed to do, sometimes it just doesn't work the way it's supposed to. A firm double tap that is slightly spaced out seems to solve it, but here's the strangest thing that I discovered. I did a hard reset and it helped and everything was normal. Then I did a restore to a backup and it helped a little (I don't want to have to start over again with a fresh fresh install, I'll save it for iOS 5). I was experimenting quitting various apps to see what would happen, since it seems like it could help. Quitting out of intensive applications such as the app store or other apps that take up a lot of memory did nothing. What does fix it immediately is force quitting mail. I've tried it with the other Apple supplied applications and it did nothing. There are only two gmail accounts there so i'm not sure what could be the problem. Anyone else out there have this/heard of this/ have any advice?
•Close all aps on the phone.
•Hold down the power button until you get the "side to power off screen" (do not power off) •While on that screen hold down the home button lightly for 20 seconds.
•If done right you should be sent to the home screen
Congratulations you just re-calibrated your home button. It should work better.
Are you sure it isn't just an intermittent hardware issue with the home button ?
I'm on my fourth iPhone 4 now, after the first three all developed problems wit the home button. In each case replacing the hardware fixed the problem, for a couple of months.