As announced in the PS Blog, the DLC costumes which have been purchased in LittleBigPlanet and LittleBigPlanet 2 will be usable in LittleBigPlanet Karting, the upcoming installment in the series.
However, the Assassin’s Creed costume and the April Fools Fragrance costume will not be available. The developers will also take some time before the costumes are fully compatible with the characters. Any new compatible costumes purchased anew will be available across LittleBigPlanet 2, LittleBigPlanet Vita and LittleBigPlanet Karting. However, the same us not the case for the original LittleBigPlanet and the PSP version of the game.
LittleBigPlanet Vita is due in September whereas LittleBigPlanet Karting is due in November.