It looks like consumers are growing tired of the Kindle Fire as Samsung releases aggressively priced tablets of its own. According to NPD DisplaySearch, Samsung knocked Amazon out of the No. 2 tablet spot in the first quarter, garnering 7.5 percent market share worldwide compared to 4 percent for the Fire. And Samsung's lead will likely continue to grow with affordable new models like the Galaxy Tab 2 10.1 and Galaxy Tab 2 7.0.

Barnes & Noble is out of the top 5 completely, which is pretty sobering when you consider RIM's poorly reviewed BlackBery PlayBook is in fourth place.

Meanwhile, Apple continues to sell more than five times more tablets than  both Samsung and Amazon combined, with the company enjoying a dominant 62.8 percent market share. The third-generation iPad combined with the reduced price of the iPad 2 make Apple very tough to beat right now. In fact, when you combine its tablet and laptop sales, Apple continues to lead the entire industry in terms of mobile PC sales.

For Amazon, it's obvious that it needs to deliver a new tablet this summer as expected. And the company will have to combine the ease of use of the Fire with more powerful components and robust features--all while keeping the price low. Some reports say Amazon is readying an 8.9-inch tablet, while others expect the mega retailer to go head to head with the iPad by releasing a 10.1-inch model.

The road ahead looks tougher for Barnes & Noble because it lacks Amazon's ecosystem, but now that Microsoft has invested $300 million in the Nook business, it could certainly help this tablet underdog.