The retail world received a shock recently when Lee Scott, Wal-Mart's very visible president and CEO, announced a January retirement. He's getting replaced by Michael Duke, the retailer's vice chairman in charge of international operations.One article points out that Scott's departure is a bit strange, given that we're upon the biggest selling season of the year. But it does reveal that Scott is leaving on a high note, as the discount giant has had a sales rejuvenation in this tough environment.Wal-Mart is such a big organization, kind of like the government, that we doubt the departure of a single executive, even if he is as visible as Scott, will make a tremendous difference. Maybe there be an accelerated focus on international growth, with Duke taking the top spot. What are your thoughts? Did Scott bring certain qualities to his position as Wal-Mart's leader that will be tough to replace? Or is this a good move for the company that will help it better succeed in the long run?