I had this problem for about 2 month and I checked all over the web for a solution no luck.I even tried restoring the phone but nothing worked.
first this is how it was i'm on firmware 2.2.1 jailbroken and yes the problem still there even after I use the offical firmware
the 456 button were not responsive
but then I read online that on the old 1.1-1.3 (2g iphone) firmwares people had the option of changing their sensitivity on their iphones. yes it gone but using ssh I was able to add the option into my iphone again
As you see the touch option not their in the new firmware but can be added
the first time turned it up all the way and then re sprang the phone and this happened
the 456 worked!!! but the 123 stopped working after that
so naturally I suspected that this is not a hardware error but more of a software error
to I went into settings reset my setting to factory
I went back to the touch settings played with it and now the entire phone works
except for one thing on the icon page the 2nd row wasn't working but I changed the touch settings to 0.7 then in ssh made some edits to the general lists and wrote a new line and now the phone works perfect
**EDIT CPJR - Link not allowed. If you'd like to upload the actual file, that will do.**
in case no one believes my firmware
general list file is here
http://rapidshare.com/files/65106710/General.plist.html
first this is how it was i'm on firmware 2.2.1 jailbroken and yes the problem still there even after I use the offical firmware

the 456 button were not responsive

but then I read online that on the old 1.1-1.3 (2g iphone) firmwares people had the option of changing their sensitivity on their iphones. yes it gone but using ssh I was able to add the option into my iphone again


As you see the touch option not their in the new firmware but can be added

the first time turned it up all the way and then re sprang the phone and this happened

the 456 worked!!! but the 123 stopped working after that
so naturally I suspected that this is not a hardware error but more of a software error
to I went into settings reset my setting to factory

I went back to the touch settings played with it and now the entire phone works

except for one thing on the icon page the 2nd row wasn't working but I changed the touch settings to 0.7 then in ssh made some edits to the general lists and wrote a new line and now the phone works perfect
**EDIT CPJR - Link not allowed. If you'd like to upload the actual file, that will do.**
in case no one believes my firmware

general list file is here
http://rapidshare.com/files/65106710/General.plist.html