Katamari Damacy is part of next week's PlayStation Store update. So if on April 30 you see a massive ball of clumped-together games where the PSN should be, you'll know what's up.
The game, first released in North America almost ten years ago, will come to PSN as a PS2 Classic. That means it's playable on PS3, but not Vita. If you need a portable fix of rollable crazy, there's always Touch My Katamari.