The team over at Valiant Studios that is currently hard at work on the pony "Dimensional Shift" project has released their Twilight 3D model, complete with three mane styles, and a fully rigged skeleton to play with if you know how to do that sort of thing. They admit the face is a little wonky, but everything else works great.
You can find the blender file over at their Google Drive, and a video detailing it below.