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Now, Amazon has followed suit in ditching Google Maps in favor of an in-house solution powered by map data from Nokia, and social network to Open Street Map earlier this year.

The reasons for these moves seem relatively simple - Apple and now Amazon compete ferociously with Google in the smartphone and tablet markets, and Foursquare didn't want to pay Google's API fees for Maps access. (The company has since sharply reduced its API prices.)

In the cases of Apple and Amazon, however, one question remains - why now?