How do I apply changes to the keyboard layout system-wide?

In GNOME's keyboard settings there used to be an "Apply System-Wide" option, but in Oneiric this is now no longer the case.

If I use the keyboard settings to change my keyboard layout, the changes are applied only in my session; on the login screen, the old keyboard layout still applies.

How can I apply a different keyboard layout to my entire system?

You might want to try the workaround suggested on the launchpad bug.

1. Edit file /etc/default/keyboard changing the lines:

   XKBMODEL="pc105"
   XKBLAYOUT="us"
   XKBVARIANT="intl"
   XKBOPTIONS=""
   

2. Run in terminal(ALT+T) sudo dpkg-reconfigure console-setup

You can find a list of all the available keyboard layouts in the text file /usr/share/X11/xkb/rules/base.lst.