As far as I know
var point = object.geometry.vertices[i];
First make sure the object's matrices have been updated.
The render loop usually calls this for you.
Then, do this:
var vector = object.geometry.vertices[i].clone(); vector.applyMatrix4( object.matrixWorld );
The vector will now contain the position in world coordinates.
You might want to read some CG reference books.
3D math primer for graphics and game development / by Fletcher Dunn and Ian Parberry
Essential Mathematics for Games and Interactive Applications: A Programmer’s Guide James M. Van Verth and Lars M. Bishop