KML is a project mainly written in PHP, it's free.
kml module with some stylewriter support
$Id: README.txt,v 1.3.2.2 2010/06/03 14:17:08 tmcw Exp $
The KML module provides a Views plugin that can format nodes, users, or any other data source in Drupal as a KML feed, accessible by Google Earth or web maps like OpenLayers and Google Maps.
KML feeds can be customized thoroughly by overriding theme functions and files in custom themes. They cannot, however, be customized through the Drupal UI. See theme functions in kml.module for reference here - adding a preprocess to the kml_placemark and kml_style theme function will allow for behaviors like scaled points and more.