[R-sig-Geo] flow visualization in lat/lon space

[Markus Loecher]

Dear list users,
has anyone experience in visualizing "flow" (e.g. with arrows or curvy lines) on maps ? For example, I would like to draw/visualize the major traffic flow patterns between counties in California.
There is a lot of flow visualziation software out there but none of them seem to create the "pictures" on true geographic maps.
(It would be really, really cool to modify kmloverlay to do this)

Thanks a lot,

Markus