If you want nodes to appear on a google map provided by the gmap_location module, you need to set up your system correctly.

from gmap_location function gmap_location_node_page() :

$result=db_query("SELECT oid, longitude, latitude FROM {location} WHERE (longitude!=0 OR latitude !=0) AND type='node'");

So, the only nodes that will appear in a gmap_location-provided map are those where the type is 'node' and the longitude or latitude are non-zero in the location table. Ok, how do we get a lat/long value in that table?read more »