An KOF XII US Debut video has been released indicating a Summer 2009 release:
Kotaku further clarifies the release date of July 2009 for Xbox360 and PS3 (link).
Also says Shane Bettenhausen, New Business Development Director of Ignition Entertainment:
“I couldn’t think of a more appropriate way to commemorate The King of Fighter’s 15-Year Anniversary than with a gorgeously animated, high-definition installment that updates the KOF legacy for a new generation. While other fighting games have abandoned the time-consuming process of creating beautiful 2D art, KOFXII fully embraces the refined aesthetic beauty that only human hands can produce.”