As of June 22, 2016, Google now requires everyone to have an API key in order to display Google Maps on your website. Details here.
If you do not have the Google Maps API key, you will receive the following error message: Google Maps API warning: NoApiKeys .
This latest version of googleMaps plugin (v3.0.25) added support for Google Maps API key. Please obtain an API key from Google and then enter the API key in the Plugin Manager.
Download here: googleMaps_v3.0.25.zip
Note that I have updated the codes for all previous Joomla versions too - Joomla 1.0, 1.5, 1.6, 1.7 and 2.5. Please make sure you download the right version that correspond to your Joomla version.