There's no official comment from Sony or Team ICO about an E3 appearance this year, but the studio may be holding out until the later Tokyo Game Show.
The Team ICO boss confirmed via his twitter account that he wouldn't be flying out to L.A. for next week's E3. The Last Guardian and the ICO and Shadow of the Colossus Collection for PS3 were all announced as delayed last month.
Sony will at least promote ICO and Shadow of the Colossus most likely, and hopefully have something of The Last Guardian thrown their way too. Cross those fingers!