Functionality for complicated motion rather than simple tweening - either lots of small tween commands generated automatically or more complicated movement built into the system (would require backend changes).
John mentioned the possibility of Processing communicating with the editor; this could be done indirectly through XML, or even directly (potentially).
From Benny Lichtner: "...it would be very useful to have a way of scripting complicated motion--maybe by working with a graph (or other visual representation) of some manipulable parameter, instead of having to tweak numbers."