According to PSMania, an Italian PlayStation magazine, Level 5 is developing Dark Cloud 3 exclusively for the PlayStation 3.
Here is what the article states (translated into english):
"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"."
Currently Level 5 is working on White Knight Chronicles which is due out in 2008 and from the sounds of it, they are already thinking ahead and have set Dark Cloud 3 into full production.
Stay tuned for more information.