I just switched back from Kubuntu to Ubuntu recently and was annoyed that CTRL+ALT+T continued to open Konsole in Ubuntu rather than Gnome Terminal. The keyboard shortcuts in the System Settings just showed that it would open the default Terminal program.

According to http://askubuntu.com/a/124718/95754 you can change that on the terminal like this:

 

sudo update-alternatives --config x-terminal-emulator