Not sure if it's working correctly. I've done the copy thing in any case since the last update took 24 hours for me.It used to be the case that you could copy the content of the beta folder to live, then the update process would identify the files it didn't need to update, thus speeding up the download.
However, I recently read that now all you need to do is make sure Enable cache check and Enable virtual cache are set in the launcher options and the download will intelligently transfer files.
I'm on a 2meg broadband connection so I so both. It's still 9 hour plus download for me