Hey all,
just stumbled upon this cool java library (+ui):
http://kmlchart.sourceforge.net/fullsite/
http://sourceforge.net/project/screenshots.php?group_id=223070
Hmm... with the dynamic symbolizers proposal implemented in
gt2 it may be possible to leverage this one in our kml
outputs.
Just daydreaming... I believe this one would have some
serious "wow" effect in GeoServer presentations 
Cheers
Andrea