One way to do that is to execute <kbd>Shift</kbd>-<kbd>A</kbd> / **Add** > **Group Instance** > *[group name]* to instance the group as a single object. Though it's basically an Empty, so we can't put an Array modifier on it, we can still <kbd>Alt</kbd>-<kbd>D</kbd> on the instance to create linked-duplicates.

**Edit:** For a more automated tool, we do need some basic scripting. I've written [a short operator][1] to do just that. Here's the key part:

    for count in count_product:
        loc = center + Vector([count[0] * self.offset[0],
                               count[1] * self.offset[1],
                               count[2] * self.offset[2]])
    
        dup_obj = bpy.data.objects.new(group.name + '_array.000', None)
        dup_obj.location = loc
        dup_obj.dupli_type = 'GROUP'
        dup_obj.dupli_group = group
        context.scene.objects.link(dup_obj)

It just creates an array of group instances along three axis:

![group_array][2]


  [1]: https://gist.github.com/adhihargo/6325992
  [2]: https://i.sstatic.net/SXR47.jpg