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From Atomicorp Wiki
To enable emacs key bindings for gnome, firefox, etc run:
gconftool-2 -s -t string /desktop/gnome/interface/gtk_key_theme "Emacs"
or run gconf-editor and go to
desktop
gnome
interface
gtk_key_theme
and enter "Emacs"
Update (17APR09):
I found I also now have to add the following to ~/.gtkrc-2.0
gtk-key-theme-name = "Emacs"