For those of you who haven't had the pleasure of seeing Michael's
spline paths in action, I added a new interactive demo on the trunk:


Click and drag the vertices to edit the spline path. It needs some
more work - eg I want to be able to add and delete vertices, which
means tracking groups (all related CURVE4 vertices for example) and
the ability to add a curve4, lineto, eg... But with a little work
we'll have inkscape-lite. Just need to add some load/save features...