Comment 6 for bug 105538

I found a better workaround. I'm using Hardy beta.

Do not use gnome's keyboard control (Ubuntu System > Preferences > Keyboard > Layout Options).
Instead follow the example in man xmodmap as explained below.

NOTE: before doing this, undo any changes in Keyboard layout options. Put the options back to defaults in gnome's keyboard control.

And, if you have done anything advanced to try to work around this issue, remove those modifications too. For example, the following is NOT needed so if you are using it, remove it (may require a restart):
 xmodmap -e "clear lock" -e "add lock = Caps_Lock"

Put the following in a text file.

            !
            ! Swap Caps_Lock and Control_L
            !
            remove Lock = Caps_Lock
            remove Control = Control_L
            keysym Control_L = Caps_Lock
            keysym Caps_Lock = Control_L
            add Lock = Caps_Lock
            add Control = Control_L

save the above as /etc/SwapCapsCtrl.kmap

then, from a terminal, run:
xmodmap /etc/SwapCapsCtrl.kmap

To make the change permanent, do this:
edit /etc/rc.local
add the following before the last line that says 'exit 0'
sudo loadkeys /etc/SwapCapsCtrl.kmap