According to a story at bbc.com, beginning January 1, 2012 Google will charge for use of the Google Maps API. The BBC says that it is rumored that Google will charge $4/1000 views in excess of 25000/day.
http://www.bbc.co.uk/news/business-15523050

One of Google's pages on Google Maps Api indicates that there is currently both a free service and a paid premier service. These both seem to be different than what the BBC is reporting.
http://maps.google.com/help/maps/getmaps/compare.html

slashdot coverage
http://search.slashdot.org/story/11/11/01/1424207/google-maps-to-charge-for-api-usage

0.35% of websites using this API = how many websites?