This problem exists since Ubuntu 12 onwards up to now (today 2012.11.18)

The bug is very simple. You cannot even change shortcut key for launching a terminal using "system settings->keyboard". The default is Ctrl+Alt+T, I want to change it to <Super>+T

In 12.04, change has no effect

In 12.10, change has effect, but cause X session to crash upon reboot, and then the shortcut is changed back to Ctrl+Alt+T

Somehow, the developer is aware of this problem and tried to correct it only in 12.10, but not in 12.04 because too many things needs to be changed. Yes, they have made it to work, but only temporarily.