Google used to display links Google Maps, Yahoo Maps and Mapquest when you entered an address or a city name.

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Now there's only a link to Google Maps next to a static map and a new option to get directions:
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... and a simplified version if you don't type an address.
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Google provides links to third parties in OneBox results if they don't have a service for that or if their service is not good enough. When their service becomes mature, there's no need for the other links. So I don't think it's fair to say this is an evil move from Google.

{ Via Blogoscoped. }</img> </img> </img>