Disgaea 4: A Promise Revisited, the Vita port of the PS3 original title, now has a Western release date. The title will be available both physically and digitally in the US on August 12th; Europe will get physical and digital copies on August 29th. Australia/New Zealand? Watch this space.
A Promise Revisited will have all the DLC available on the PS3 version, and also contain all-new characters, story bits, spells, techniques, weapons, cameos, and music. Given that Disgaea games always have a great deal of content in the first place, this is just icing on the cake.
Also, Nippon Ichi has announced a Limited Edition for A Promise Revisited:
The Limited Edition will include a special box, a poster, a set of three keychains, and a cloth, and will run you US$49.99, instead of the US$39.99 for the standard edition. Check with your local retailers for pricing and availability.