Nintendo confirmed that both channels would be released in November in Japan. Seeing as America got Check Mii Out the same day Japan did, I'd assume that we'd be getting this channel in November.
It'll have demo movies for upcomming Wii games, and also make your Wii function as a download station for the DS, so that you can download demo movies and playables on you DS, and possibly bonus content for DS games. Can we say Mystery gift for Pokemon?