Microsoft’s ad exchange business has been fairly quiet since it bought AdECN about two years ago, but as challengers like Google (NSDQ: GOOG) have ramped up their ad exchange and display business, it is making some moves of its own. Microsoft (NSDQ: MSFT) just struck a partnership with open-source ad server OpenX Technologies. The multi-year agreement has OpenX becoming a Microsoft Preferred Partner, and Microsoft will refer publishers it works with to OpenX and its ad serving products. In return, OpenX will steer its publishers to Microsoft’s Content Ads program – as well as other products that may be developed in the future. While OpenX runs a display-ad exchange, the company’s CEO Tim Cadogan told paidContent that this arrangement is separate from the AdECN program.

While the partnership with OpenX appears to be aimed more at capturing some of Google’s AdSense contextual ads business, it also comes as Microsoft is looking to build up AdECN. While the Microsoft program is one of the largest exchanges, along with Yahoo’s Right Media, the business is still coming out of the nascent stage and remains fairly wide open for Microsoft, Yahoo (NSDQ: YHOO) and Google to become the lead.

Apart from Jeff Green leaving his post as COO of AdECN early last month, the unit hasn’t been heard from much. MediaMemo’s Peter Kafka reported last week that the Microsoft unit has been “running a pilot of its Federated, real-time bidding technology within Microsoft for the past several months and will be rolling that product out to a select group of participants in the coming months.” Whether OpenX will get a piece of that business could be determined by the work it does now.

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