According to this Thread (thread-45085) the Tabbed Menu is going to be Published.
But I found that
http://www.learnmybb.com is allready using this.
So, How can I install it in my forum? Where to get the files?
That's why I gave you the link, to read.
It was published, but for MyBB Central subscribers only. Subscriptions are now closed, so you can no longer get the plugin.