Thanks for creating this incredibly useful plugin! I can't belive that after all these revisions this functionality has still not been included by default in the core WordPress engine.
Minor bug: When in post editing page, clicking on the 'Copy to a new draft' link works as expected, BUT when publishing the copied post, its Permalink is not automatically updated as it did in the previous versions of the plugin.
The permalink in the copied post remains "copy-of-(original post permalink)"*
*I should note that I have set the plugin to append "Copy of" at the beginning for the copied post title.
So right now I have to manually delete the old permalink every time before I publish the post. This forces the permalink to be re-created using the new post title.