Unlike some Web-based phenoms, the location check-in service Foursquare has an obvious potential business model: local ads based on your geographic location, perhaps coupled with inferred interests from your previous check-ins.

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Less than a month after photo social network Instagram caught huge flak over advertiser-friendly changes to its privacy policy (and claimed it was misunderstood), another social network, the location check-in service Foursquare, has announced revenue-friendly changes to its privacy policy.

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But the company is mainly built on the location-based check-in service.

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Time magazine, for example, has formed a partnership with Foursquare, a location-based mobile check-in service, for the conventions, in which Time has provided content that users can unlock when they get to certain locations in Tampa and Charlotte.

WSJ: Online Media Will Star at the Conventions

Last year, Facebook also unveiled a check-in service for its phone apps that allow users to volunteer their location to friends, and also find deals from nearby businesses.

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Notably not in attendance (or at least, not visible at the event) were location service startups Foursquare and Gowalla, much of whose value lies in the rich database of check-ins they are sitting on.

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