READ: This app is a demo for Unity3D developers. If you don't know what Unity is, please don't download this app.
The app demonstrates how to share content in Unity. This will enable you to take a screenshot and share it through an external app of your choice.
You can get the code and more info on my blog: http://www.daniel4d.com/blog/sharing-image-unity-android/
If you're a Unity developer, and you have any questions about this, feel free to contact me.