It looks like the newest version of the Classic Controller is Japan-only, at least for now.
Last week Nintendo unveiled the Classic Controller Pro, an “upgraded” version of the existing Classic Controller for the Nintendo Wii. However, Nintendo representatives said nothing regarding its availability outside of Japan, where it has been slated for a summer release. Today, Gamespot received confirmation from a Nintendo of America representative that there are no known plans to release the controller in North America, and CVG received the same confirmation for Europe.
The Classic Controller Pro has a revised placement of the zL and zR buttons to the back row, similar to a Playstation DualShock controller. It also has lengthened handles, and a different placement of the wire that connects to the Wii Remote.