The latest version of the David and Wayne Maddison's Cartographer module for their program Mesquite can export KML files for Google Earth. They graciously acknowledge my crude efforts in this direction, and Bill Piel's work -- he really started this whole thing rolling. So, those of you inspired to try your hand at Google Earth trees, and who were frustrated by the lack of tools should grab a copy of Mesquite and take it for a spin.