UPDATE - A full announcement from the company is due next week, so expect a full unveiling, and perhaps news of some other titles then.
A leak of NIS' release schedule in Japan showed, rather briefly before the document was removed, that Disgaea 3 is down as Sony Vita launch title. The first two in the series (Hour of Darkness and Cursed Memories) were well rated on the PSP and spawned the off-spring Prinny games.
The third game in the series was released in 2008 on the PS3 and warmly welcomed in the west, with a fourth title due sometime. A Vita release is pretty much a no-brainer as the series has fans around the world and should be an easy update for NIS.