Sony has announced Cross-Buy, a program for cross-platform Vita and PS3 games that grants you a copy of the game on both platforms if you buy one.
PlayStation All-Stars: Battle Royale will be the first Cross-Buy game. Owners of the PS3 version of the game will be entitled to a copy of the Vita version, and vice versa.
Other participating titles will be Sly Cooper: Thieves in Time and Ratchet & Clank: Full Frontal Assault, with more to come in the future.
Source: Sony Gamescom conference