According to Italian Playstation magazine PSMania, Level 5 who are currently working on White Knight Chronicles which is due out later this year are rumored to also be working on Dark Cloud 3 which will release exclusively on the Playstation 3 in 2009.
The translated article states
"One of our infiltrates, has revealed that Level 5 is working on a new Dark Cloud exclusively for the PlayStation 3. This title will come out in March of 2009, and will be developed using a new open-technology, the Japanese style "Kumo Engine"