i think it's software related issue that causes the home button being not responsive..it looks like hardware problem, but i do think it's software problem..

before sending your phone for warranty claim, try this on your phone..hold the power button (on top of the phone) until the "SLIDE TO POWER OFF" screen comes out..now, press the home button repeatedly with normal pressure (not too hard) for 30 seconds..after the 30 seconds have elapsed, the "SLIDE TO POWER OFF" screen will self-cancel, bringing you back to your homescreen. after that, your home button might work..

i don't know if it will work on you guys..but it did work for me..

cheers...