Now Wal-Mart's (NYSE:WMT) just rubbing it in.

Fresh from announcing it would stop carrying the Kindle tablets sold by Amazon.com (NASDAQ:AMZN), Wal-Mart just rolled out another nationwide promotion of Apple's (NASDAQ:AAPL) competing device. According to Reuters, Wal-Mart stores will be offering discounted iPad options including a free $30 iTunes gift card to customers who buy the tablet over the next 30 days.

Millions of consumers might be conflicted about which tablet to pick this holiday season, but the nation's biggest physical retailer is certain: It has placed its bet on Apple.

Of course, Wal-Mart is also responding to Amazon's encroachment into its space. The two giants of the physical and e-retail world have been on a collision course for some time now. Amazon should reach $22 billion in sales this holiday quarter, up from $17 billion in the year-ago quarter. And online sales continue to grow much faster than physical store purchases. The Kindle tablet is a major strategic push to keep that growth going. Amazon hopes to boost both digital and physical goods shopping through the company's tablet devices.

Wal-Mart understandably doesn't want to help that strategy along. And the company isn't alone in the retail rebellion against Amazon's tablets. Target (NYSE:TGT) pulled Kindle devices from its shelves back in May. The company was reacting to Amazon's "showrooming" strategy, which Target thought had gone too far. Company executives told their vendors at the time that "what we aren't willing to do is let online-only retailers use our brick-and-mortar stores as a showroom for their products and undercut our prices."

Apple's iPad offers no such threat to Wal-Mart, and so the working relationship between the companies should only deepen. Promotional iPads were a key part of Wal-Mart's successful Black Friday events last month, after all. As Apple hopes to push a more affordable product line and as Wal-Mart tries to fend off e-commerce challenges, the two companies have every reason to team up for the holidays.

Fool contributor Demitrios Kalogeropoulos owns shares of Apple. The Motley Fool owns shares of Apple and Amazon.com. Motley Fool newsletter services recommend Apple and Amazon.com. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.