Angry Birds Rio free on Amazon's Appstore for Android

Amazon has opened its Appstore for Android, and is giving away a free, special edition Angry Birds to the three and a half people who don't have it yet.

Angry Birds Rio is a tie-in to the upcoming film from Ice Age creators Blue Sky Studios, and is an Amazon exclusive. It normally goes for 99 cents.

The app is available within a "Today's free app of the day" box, suggesting Android users may want to check back daily for special deals.

The store also includes a neat "test drive" feature allowing you to preview apps from your browser.

Meanwhile, Bloomberg reports Apple is suing the online retail giant over its use of the term "appstore", which it claims to hold a trademark for.

Apple has alleged Amazon used the term to "solicit software developers" throughout the US, and said customers will be confused by the closeness of the two stores' names.

Thanks, Joystiq.