The PlayStation Vita was essentially pitched as a portable PS3. While that's not quite accurate in raw technical prowess, Sony and some third-parties have been eager to produce cross-compatible games that can work in tandem between the platforms. So it only makes sense that PlayStation All-Stars Battle Royale, Sony's own franchise-blending super group of a game, would fit this mold as well. We've gotten one strong new hint that indicates that's the case.
A Superannuation tweet points to a domain registration for BattleRoyaleTheGameVita.com. It was registered on May 24, to (shock) Sony Computer Entertainment America. The conclusion seems pretty obvious.
This is likely to be part of Sony's revelations during E3, as it makes the case for Vita's upcoming year after a somewhat rocky start. We'll be there to cover the official announcement with any as-yet unknown cross-system features.