Synchronise Google Earth places across multiple computers using Dropbox. The instructions are currently specific to OS X but can be extended to Windows and Linux.
The ~/Library/Application\ Support/Google\ Earth is moved to a google-earth-sync directory under a Dropbox container directory. A symbolic link is then made to this directory.
The entire Google Earth data directory needs to be synchronised instead of just the myplaces.xml file because of how Google Earth backs the file up. During the backup process after quitting Google Earth, myplaces.kml is renamed to myplaces.backup.kml and then copied to myplaces.kml. If only the myplaces.kml file were to be synchronised with a symbolic link then the synchronisation process would break after one cycle because the backup file would then be the symbolic link.