Shattered started on it's own, with Martyn and Mikkel building their own pseudo-wrapper around Ogre. I came along and realized that such a wrapper just wasn't going to work and began building
Ogre.rb. Now that Ogre.rb is in a usable state, Shattered has been converted to use it.
So as it stands, yes and no. Look at shattered as a game development library. Ogre.rb is just one component of this library to provide 3D rendering capabilities. Shattered will eventually have links into audio (OpenAL / fmod / ...), physics, etc.
Jason