The Jaco arm can now execute a joint trajectory with the implemented arm controllers in Gazebo. The trajectory can be computed with MoveIt!. Collision objects (like the cube to be grasped) are also sent to MoveIt! via the object information pipeline described in the wiki.
There has also been work on existing and new tutorials on the wiki, to which I would like to refer to in general. Probably the wiki contains more up-to-date information than this blog.