When 4.0 launches you'll notice a new tab in the preference window labeled "Keybinding Import/Export" from there you'll be able to save out your current keybindings to a file which you can then load on another character. When you save the keybinding they'll show up in a list which you can then select to preview and load those saved bindings. The list of keybindings you can import is shared across all your characters and saved locally on your computer. The keybindings are saved out to an XML format much like the UI Profiles are, so you'll be able to share them with friends and such.