Andrew Davis from Namco Bandai Games, confirms Orochimaru, Itachi, and indirectly Team Hebi in an interview with GameTrailers! Also Kiba, Akamaru, and Yamato have been revealed!
Also thanks to Kobe from SI Forums for showing us Kiba and Akamaru from the trailer yesterday. If you want to see them in the trailer, look between the 45, 46, 47 second mark or at the stills below!
Thanks to PHANTOM for pointing out Yamato (55 seconds into the trailer)
Check out the Naruto Shippuden: Ultimate Ninja Storm 2 section!