Prevent dictionary from coming up in Lion
This applescript will turn the option off. Make sure that access for assistive devices is turned on, which is found in Universal access.

tell application "System Preferences"
    set current pane to pane "Trackpad"
    tell application "System Events"
        tell process "System Preferences"
            if window 1's tab group 1's checkbox 3's value is 1 then
                tell window 1's tab group 1's checkbox 3 to click
            end if
        end tell
    end tell
    quit
end tell