I just noticed the "The KML Handbook: Geographic Visualization for the Web" by Josie Wernecke is out on Safari Rough Cuts. It looks like it has some interesting tips, not really a programming book per se, more of an expanded version of Google's documentation. The subtitle is interesting to me- "for the Web". A couple of years ago it would have just been for Google Earth, but KML is on its way to becoming the new shapefile. Next I want JSON.