The rumor seems to have originated from a PS3Forums posting titled "Game Informer to reveal the Team ICO game?" with a transcribed article, but no scans, photos or links.
Fortunately, Andy McNamara of Game Informer poked his head into the NeoGAF thread on the matter, casting even more serious doubt on the preview. According to GI's Editor-In-Chief "This is not in the next issue of Game Informer. The new GI has something new...but its from another much-loved developer."
Too carefully worded? What if it's in the Game Informer issue after that? McNamara tries to bring sanity to the Team ICO next-gen rumor circus. "Trust me...we'll try to get the next Team ico game....love those guys" he wrote in a follow up post, "But I wouldn't slam the door shut on the next issue yet."