As of Ubuntu 12.10, the relevant dconf path is /org/gnome/empathy/conversation/spell-checker-languages. Change the value to whatever language you want (e.g., "en-US").
As of Ubuntu 12.10, the relevant dconf path is /org/gnome/ empathy/ conversation/ spell-checker- languages. Change the value to whatever language you want (e.g., "en-US").