GMaps 1.0 introduces the tabs on information popup box for the markers; however, at this time, the only way to change the text is to "hack" the code.  A future release of the product will make this all configurable. 

If you wish to change the text,  you may edit the googleapi.class.php file to make the change.  This file can be found in the joomla root/components/com_gmaps/classes folder.