Today Google announced that they are enforcing free usage limits on the Google Maps API. Beyond the free limit of 25,000 views per day, sites will start having to pay $4 per 1,000 views. They will automatically charge your credit card based on these usage fees and it's not clear if you can set a "cut-off" limit or if it will have the similar suprises as overseas cell charges.
I find this is a bit of a surprising action from Google. In 2005 they changed the mapping and geospatial web by providing a powerful, easy to use great API (eventually), and primarily free of charge slippy map platform. The term "GoogleMap" became synonymous with being able to pan and zoom through the entire world without any reloading of the page or poor user experience. Since then, there have been millions of sites that have used GoogleMaps to provide simple map views and location services. Assumedly this information has been of huge value to Google in understanding interest, spatial-context, and generally eyeballs to Google tools and content.
Google has also worked to monetize maps, often subtly through sponsored map markers, and other times more directly through in-map ads. Each of these decisions brought discussion and disent but it was difficult to argue with the fact that the tool was still free to use. Google has clearly put real value in content and engineering into Google Maps. The quality of geocoding, data availability and power of the API has always been extremely capable and arguably the best of breed.
Now, with a very direct pay requirement being imposed this will dramatically change the adoption of GoogleMaps. Developers will have to consider very carefully how they will afford the potential - and optimistically likely - fees that the service will require as it becomes successful.
Fortunately, there are still a few really good alternative options for developers of sites if they can't afford the usage fees. MapQuest has really embraced the future of open by supporting and integrating OpenStreetMap into their sites. Microsoft Bing maps are very capable and there are many more - not least of which is a developer "rolling their own".
This interesting change by Google also validates abstraction libraries such as Mapstraction. Mapstraction provides a common API where a developer can easily switch between map provider libraries without having to rewrite their code - something that would likely cost much more in the short term than paying for usage fees. On GeoCommons we use ModestMaps to be able to switch to any map data provider service.
I'm very interested to see the general developer reaction to this change.