OneNote for Fire Phone is available in the Amazon Appstore for Android on July 24, Microsoft execs said. This isn't a version of OneNote optimized for the Fire Phone; it is the existing OneNote for Android app that is now available in the Amazon Appstore for Android
While OneNote for Android was developed and optimized for the phone and not Android tablets, it can be installed on Android tablets, as well. That means the version in the Amazon Appstore for Android can be installed on Kindle Fire tablets. (The image embedded in this post is what OneNote looks like running on the Kindle Fire HDX.)
Microsoft is still working on a suite of touch-first Office apps for Android tablets. That suite will be released before the end of calendar 2014, according to my sources. It will likely be free but require a subscription to Office 365 to unlock functionality, the same way that the Office for iPad suite does.
Delivering productivity apps and services across all of the top mobile devices is a new priority for Microsoft, and no doubt a key reason the company has been quick to make Skype and OneNote available on Amazon's mobile devices. The fact Evernote is already in the Amazon Appstore for Android probably also spurred the OneNote team to release its apps there, as well.