A comment made in a PSN blog interview with SNK's Kei Yamamoto mentions that the new King of Fighters XIII game could make its way to Vita in one form or another. Given the decent effort that Marvel vs. Capcom 3 is getting on Vita, I'd hope this would happen sooner rather than later.
PSB: PlayStation Vita is turning into the ultimate portable machine for fighting games. What do you think of the hardware? Any chances we’ll see a KOF title for PS Vita in the future?
Yamamoto: The PlayStation Vita controls well, the titles being released are appealing, and user impressions are good, so I am very interested in it, not just as a developer but as a user as well. Personally, I’d love to work on a KOF title for PS Vita if the opportunity arises.