The Last Guardian has had a rough developement run. After being leaked early by some jerk, it was announced officially during Sony's 2009 E3 press conference. Since then, news has dried up, and no hands-on time has been given to the press.
We found out why just months ago: Creator Fumito Ueda left Sony, as did other key production staff. There were even some rumors of the title being cancelled. But Sony invested big bucks into this console-defining game, so rather than let it die, Sony has called for reinforcements.
According to VP of Sony Worldwide Studios Shuhei Yoshida, other internal Sony devs from the West, such as Sony Santa Monica (the team responsible for many PSN titles, and the God of War series), have been pitching in to help see The Last Guardian through till the end.
Yoshida continued saying that although TLG is playable, it's not at the point yet where they can begin planning a release.
Hopefully we'll finally get some hands-on time with it at this year's E3.