transform feedback

hello.
Is possible to retrieve the vertexes of the geometry shader or of the vertex shader on the cpu?
For example(but it’s only an example for try and understand), if i have a skinned mesh , is possible retrieve a pose of the mesh after the vertex shader transformations?
I read about the “transform feedback”.
how it work if is possible? there is a link?

thanks.

try
http://www.opengl.org/registry/specs/ARB/transform_feedback2.txt
http://www.opengl.org/registry/specs/ARB/transform_feedback_instanced.txt