The $199 Kindle Fire, which features a 7-inch LCD display, is the first color tablet to challenge Apple's iPad in the consumer market. Amazon shipped 4.7 million Fire tablets in the fourth quarter of 2011, enough to grab 16.8 percent of the market, according to IDC. Apple shipped 15.4 million iPads in the same period, up from 11.1 million in the third quarter.

So if the Fire is a hit with US consumers, why isn't Amazon selling its tablet worldwide?

"My guess is that they don't have foreign-language video and music content deals lined up, and those are much more important for the Fire [than for the E-ink Kindle Touch]," IDC analyst Bob O'Donnell told PCWorld via email. "There could be issues about localizing apps as well."

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Video and audio content are essential to the Kindle Fire's appeal. A Fire without streaming services such as Netflix, Hulu Plus, Pandora, and Amazon Prime--or the international equivalents of these apps--would weaken the tablet's allure.