It's not supported. And in the vast majority of case you're better off using the built-in maps in Splunk 6.
But if you want to know whether it works, then the answer is probably yes. There are still a few narrow edge cases dealing with large result counts and/or Advanced XML dashboards where it may make sense to use Google maps. Just remember you're going to be largely on your own if it breaks later.
It won't work out of the box if you're using SSL, but you may be able to fix it with the following code at line 29 of $SPLUNK_HOME/etc/apps/maps/appserver/modules/GoogleMaps/GoogleMaps.js