'Project [M]' from NCsoft has finally been revealed as a new, graphically stunning MMO entitled Blade and Soul.
Last year during E3 2007, Sony revealed that they had entered into an exclusive deal with NCsoft to produce new titles exclusively for the PlayStation 3. This contract included titles from both existing intellectual properties owned by NCsoft as well as new IPs.
With Blade and Soul being one of the first new titles announced from NCsoft since Aion: Tower of Eternity, it's very likely that this is one of the PlayStation 3 titles from the contract. Since there has yet to be official confirmation from NCsoft, take this as pure speculation for right now.