Amid all the buzz about Facebook's new location-based check-in service Facebook Places, it's interesting to note that Amazon.com is racking up more patents for location-based search technology. The ecommerce giant on August 10 received two patents related to providing location-based search information for mobile devices.

The patents were filed in June-July last year, though they appear to originate from applications dating back to 2005. They are assigned to A9.com, Amazon's internet search unit based in Palo Alto. It's not clear what Amazon plans to do with these patents, or if they are part of any future product plans.

Here's the abstract for one of the Amazon patents, No. 7,774,002, for "Providing location-based search information":

Common search queries can be provided that are associated with a location. A location of a mobile device can be determined, and common search queries associated with the location can be transmitted to the mobile device. A user of the mobile device is able to execute the common search queries from the mobile device.

The other patent granted August 10 is for "Providing location-based auto-complete functionality." In July 2009, Amazon also received a patent for a "System and method for providing search results based on location."

All of the patents list as inventors Ruben Ortega, Robert Frederick and Barnaby Dorfman, all of whom have since left Amazon. (Ortega is now a director of engineering for Google in the Seattle area; Frederick has his own mobile app development company Gripwire; and Dorfman is CEO of online recipe startup Foodista.)

A9 started out as an Amazon effort to build a Google-like internet search engine. Amazon pulled back on that project in 2006, but kept the A9 unit, which works on product search on Amazon sites. A9 has also gotten into mobile search, acquiring an image recognition startup called SnapTell in June 2009.

Perhaps Amazon is contemplating some location-based feature for its mobile shopping apps. The company recently disclosed it's done more than $1 billion in sales through mobile devices in the past year.

Amazon has also shown an interest in social networking. The company received a patent for a social networking system in June, and recently launched a new feature that lets people connect their Amazon and Facebook accounts to get gift recommendations for themselves and their friends.

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