Update: Tetris Party is now confirmed on the official site to be coming out on the 20th October. That's this coming Monday!
Tetris Party features a whopping 18 different game modes to choose from, 10 of which have never before been seen in a Tetris title. As an added bonus there will also be full Wii Balance Board support as well as local and online multiplayer support. Those of us here at WiiWare World can't wait to get our hands on this newest incarnation of Tetris.
Darts Wii and Brain Challenge were also released in Japan on the WiiWare service today as well. While we haven't heard any news of a Darts Wii release outside of Japan as of yet, we do know that Brain Challenge will be heading to the US and Europe at some point in the near future.
We'll have any new information on these three titles as it becomes available.