The trailer ends with the revelation that Rising , which has long been out of the public eye, is now being "produced" by Hideo Kojima's own team, but is being developed by Platinum Games, the studio behind Bayonetta.
While the trailer, which is full of gameplay footage, looks legit, since it hasn't been run yet at the show there's no way to know whether that conclusion is the real deal.
It would make for an interesting development if it is, though, seeing as Platinum looked into our eyes and told us that rumours suggesting this back in June were "not true".
UPDATE - Yup, ran just as you see it here. 100% official.