Surprised no one made a thread yet (I think...).
"Muramasa: The Demon Blade is a action role playing game developed by Vanillaware and published by Marvelous Entertainment in Japan, Rising Star Games in Europe, and Ignition Entertainment in North America exclusively for the Wii. The game was released Japan on April 9, 2009, and is set for release in North America on September 8, 2009, and in Europe on sometime in November 2009."
You can play as either Kisuke or Momohime:
"Kisuke, who has lost his memories, is a fugitive being chased for a crime he no longer remembers. His only desire is to find a certain katana. After defeating his arresters, he meets Yuzuruha who offers to guide his path. Meanwhile, Momohime, after being possessed by a foul swordsman, Jinkuro Izuna's soul, is forced to flee her castle and accept Jinkuro's offer to complete his plan."
taken from wikipedia 
http://en.wikipedia.org/wiki/Muramasa:_The_Demon_Blade
Pretty much a 2-D side-scroller, much like Odin Sphere.
From what I've read you can have 3 different kinds of swords "on you" at a time (out of the over 100 swords). They are categorized into 1 of 2 groups. Tachi and Ōdachi. Tachi is a small, more agile and swift sword. Ōdachi is bigger, slower, but a more damaging sword. Each sword has its own special attack/technique, and your sword has a durability bar, which overuse results in it breaking and renders it useless for a short period before it regenerates.
I believe the game will retain its Japanese audio and will have English Subtitles in the North American release due to it being heavily influenced by Japanese mythology.
Thoughts? =]