Since fall 2008, Walmart has been undertaking an ambitious plan to re-engineer its stores in an effort to create an environment that its 140 million weekly shoppers will find easier and more pleasant to shop. The company's efforts to improve the shopping experience also entailed a re-evaluation of its in-store marketing practices to identify programs that would better resonate with customers -- especially the "Moms" who account for more than 70% of the chain's business.