The Appstore will feature localized content as well as the apps available in other market. It's also going to get the same features found in the other markets, including the Free App of the Day, in-app payments, and trial modes which let you test an app before you buy it. Games and apps purchased from Amazon can be used across most Android devices, including Amazon’s own Kindle Fire range of tablets.
This news comes as no surprise given that Amazon started accepting submissions from Japanese Android developers at the beginning of October, and Amazon's own Kindle Fire tablets went up for pre-order on Amazon.co.jp over a month ago. The tablets are expected to ship on 19 December.
Speaking of the Free App of the Day, I also run a helpful little reminder service which you might be interested in. I track each day's free app and post it to an RSS feed. You can also find the free apps on the Appazonia page on this blog.