The rumors were true, unfortunately.
ICO and Shadow of the Colossus creator Fumito Ueda has indeed left Sony, as the company revealed in an official statement .
However, although he is no longer a part of Sony, the statement says Ueda is "committed to completing" his current project, The Last Guardian . He's working on a contractual basis with Sony; after that, he's free to do what he wants. Those looking forward to his current title may have to wait, though, as the game doesn't appear to be on the horizon. Worse, Sony has lost one of the premier interactive entertainment minds and visionaries.
Although he doesn't have a slew of titles to his credit, ICO and Shadow of the Colossus remain two of the most beloved and critically acclaimed games of all time. Today, developers will often cite Ueda's productions as the inspiration(s) behind current concepts and ideas.
We don't know why Ueda left Sony, but we certainly hope The Last Guardian will make a lot of headway in 2012.
Related Game(s): The Last Guardian