Despite being pilloried by the public lately, a banker’s lot can’t be all that bad. At least, that’s what Wal-Mart executives must be thinking. Over the past year, they have unveiled one plan after another aimed at getting a bigger share of the U.S. retail banking market, which could be good news for some and bad news for others. It started in August 2009 when Wal-Mart’s “Money Centers” began offering bill payment services. Then in March of this year, the Arkansas-based retailing giant announced that it will be increasing the number of Money Centers from 1,000 to 1,500 by the end of 2010. In May, the company introduced a new cash-back promotion for gas bought with Wal-Mart’s prepaid, reloadable debit cards, followed shortly afterward by the retailer’s purchase of a 1% stake in Green Dot, the prepaid card provider that Wal-Mart has been working with for the past three years. And beginning this summer, Wal-Mart’s U.S. customers can apply for small business loans at its membership-based Sam’s Club stores.…