In my experience, on not just my own iPhone 4 but also on my girlfriend’s, WD-40 restores the responsiveness of the iPhone’s home button to basically like-new condition. I just sprayed a little bit of WD-40 directly on the button, then pressed the button rapidly a few dozen times, tested its responsiveness afterwards, then repeated the process two or three times until it began to improve.
I highly recommend that you do not use this procedure.
Also, side rant. He mentions this in passing,
There has also been talk of the button needing software recalibration. I don’t know if that approach works or not,
It doesn’t. The gist of this “fix” that’s been floating around the internet is that you open up the stocks app, hold the power button down until the “slide to power off” switch appears, then hold the home button down until the app quits. This is complete and utter stupidity. This is the method for force quitting an application that has become so unresponsive that you can’t get back to the home screen or the multitasking tray. This has nothing whatever to do with “calibrating the home button”. As if it would need calibrated. It’s a hardware button. You click it, it does things. If it doesn’t, something is wrong. End of story
/rant