Fire TV may have a unique user interface, but beneath it all, it runs Android. That means you will be able to sideload apps on the device. Android app developer Koushik Dutta is known for developing apps that stream photos, videos, and music from Android handsets. Content mirroring with Amazon Fire TV is also possible as this video shows:
The demo has been done using AllCast. Since the Fire TV has better hardware than most other set-top boxes, it is not a surprise that it performs extremely well in these tests. This actually makes the Fire TV a more tempting device. Too bad I had to return mine for wireless issues (more on that later).