According to an official Nintendo press release, all new Wiimotes that are sold separately (including Wii Play) from October 15th onwards, will come with this free cover. Those that already own the console and Wiimotes can order them for free from Nintendo.

Now isn't Nintendo being generous? First it was free improved replacement straps and now cases too! Orders are being taken now but they won't be shipping until the above date (at least for the US and Japan).

I have two Wiimotes but never bought covers for the. I just give them a clean with a cloth after use but I might order these. The top half looks a little odd...