I’ve been sitting on this email from Kevin Martin about an update to the popular Export to KML extension for ArcGIS Desktop.

just wanted to let you know that there is a new version of ExporttoKML available that corrects the problem of displaying extruded polygons in the newest version of Google Earth. The were not displaying correctly due to a change in the KML rules. That’s been fixed, and a couple of other improvements were made.

If you want a simple way to get a shapefile into KML, this is one of the best ways.