WiiSpeak peripheral, planned for release in Japan on November 20. Nintendo of America plans to release the channel stateside on November 16. It'll be a free download with the WiiSpeak.
According to NOA's announcement, it works for up to four groups, with each participant in each group represented by a Mii. The Channel allows sending of voice messages and photos. It's simple, yes, but at least people who buy the peripheral outside of an Animal Crossing bundle will have something to do.