TotalVideoGames.com and RPGamer.com report that this week's issue of Famitsu confirms that Eternal Sonata, or Trusty Bell as it's known in Japan, is set for release for PlayStation 3 in Spring 2008.
A page scan of Famitsu is included. Please see Alternative Sources.
Famitsu reports some details of the PS3 version: it will contain two new playable characters, Crescendo (who uses a mace and shield) and Serenade (who uses a staff,) and let playable characters change costumes during the course of the game. (Translated by Shin from the GameTrailers.com forums.)
Several members from the GameTrailers.com forum point out that the screenshots from the scanned pages come from the PS3 version - because the interface layout looks different from the Xbox 360 version.
The PS3 version will be released in Japan. It is unclear at this moment whether the PS3 will have an English version.