PlayStation All-Stars Battle Royale is more than a celebration of all things PlayStation, it's a celebration of all things gaming. And there's nothing more "gaming" than a title everybody loves but nobody bought when it originally came out. See Shenmue, Okami and, of course, Ico. And there's every reason to believe that that last game might be getting its spot in the PlayStation-based fighter.
It almost seems silly to think that there wouldn't be some reference to ICO in fact, it's one of the most popular and respected games from the PS2 era and, actually, the HD collection seems to have done alright. The above shot, taken from an image posted on The Paul Gale Network, was put together by an eagle-eyed user on Neogaf and, once you see it side-by-side like that, it's difficult to see anything else.
It seems Superbot are very focussed on giving the fans what they want for PlayStation All-Stars Battle Royale, and I for one can't wait to see some official announcements start rolling out.