Virgin Mobile USA (NYSE: VM), which recently closed down its Sugar Mama program that subsidized minutes for users if they watched some ads on its website, is going to file a lawsuit against the operator of that program later this morning, sources have confirmed to us. The company, online ad tech firm Ultramercial, allows users to get something free (or premium) in exchange for them watching ads. Salon.com has been using its tech/format for years now, and VMUSA adopted it in 2006 to launch its SugarMama program.

More on the reasons for the lawsuit tomorrow when they file.

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