There have been a few rumors spreading that suggest Ninja Gaiden Sigma will be released for the Xbox 360 as well as the PlayStation 3. These rumors have now been crushed in a recent interview with director, Yosuke Hayashi, at CVG.
Hayashi said, "I would take that rumour as proof that people's expectations for Sigma must be very high. But it is just a rumour.
It doesn't seem like the company has any plans to release the game on the Xbox 360 so it should remain a PS3 exclusive.