Online retailing giant Amazon on Tuesday launched its Appstore for Android, an online marketplace for the mobile OS that drives many smartphones and, increasingly, tablet devices. Aside from bringing its prowess in e-commerce to the new store, Amazon is also offering Android users an interesting lure: one paid app for free each day, starting with a popular new Angry Birds title.

But waiting in the wings is a spoiler: Apple has sued Amazon for using a name that it deems too close to its own App Store. Apple is currently trying to secure a trademark for the term "App Store."

Amazon's new Appstore for Android is a replacement, of sorts, for the Android Marketplace that Google bundles in Android. Unlike Google's offering, however, the Appstore is highly curated and doesn't suffer from an overabundance of absolutely worthless and borderline illegal crapware. On the flipside, it's also less voluminous, at least for now: Whereas Google claims more than 170,000 apps (most of them horrible), Amazon has fewer than 4,000—for now.

"Our customers have told us that the sheer number of apps available can make it hard to find apps that are high-quality and relevant to them," says Amazon Vice President Paul Ryder. "We've spent years developing innovative features that help customers discover relevant products. By applying these features, we're aiming to give customers a refreshing app-shopping experience."

The Appstore offers other advantages. Amazon offers the ability to test apps before you purchase them, using a web-browser-based Android emulator. And customers who do purchase apps can return them for a full refund within the first 15 minutes. All purchases and free downloads are tied to the user's Amazon.com account, so they can be installed on multiple devices.

Best of all, Amazon is temporarily offering a single paid app each day for free. On opening day, this was Rovio's blockbuster title Angry Birds Rio, a follow-up to the original Angry Birds, one of the most popular mobile apps of all time. And for the first time, Amazon is offering ad-free versions of Angry Birds, and another follow-up called Angry Bird Seasons) on Android; these apps cost 99 cents at Amazon.

According to Amazon, the Appstore is generally compatible with any device running Android 1.6 or later. The exception, for now, is devices sold through AT&T, but AT&T will be providing an update for its Android-based phones and tablets to enable this compatibility. The Appstore is US-only for now, Amazon says.

Meanwhile, Apple is suing Amazon for using a slightly modified version of its App Store brand; Apple's App Store sells apps for the iPhone, iPad, and iPod touch. "We've asked Amazon not to copy the App Store name because it will confuse and mislead customers," an Apple spokesperson claims.

For more information about the Appstore for Android, you can visit the Amazon website.