Context, please? I have no clue what Battle Jump is. I'm thinking it's a feat, and it conjurs in my mind an image that matches that of Leap Attack from Complete Adventurer.
If it's a feat, it's probably not in any of the "Complete" books, the Player's Handbook II, Miniatures Handbook, Heroes of Battle, Monster Manual, or any of the "Race of..." books. Otherwise I'd likely remember stumbling upon it, because it sounds like a very cool melee tactic.