Wheee! That was easy..
http://bit.ly/97w6oo
I didn’t see this mentioned during install, or in code comments, but I may have missed it:
To make this work, the user has to edit the "googlemapstv.api_key" System Setting and enter your own site’s Google Maps API Key.
For multi-site setups, if you have or need different API Keys for the different Contexts, just create your own "googlemapstv.api_key" Context Setting.
I guess the most obvious place to note this would be the Instructions section on the Package’s page.