Capcom isn't saying much about Dragon's Dogma: Dark Arisen, beyond the Tokyo Game Show trailer above. We've got dragons and Arisens, so I guess that's good enough.
The trailer, shown at Capcom's booth at TGS, reveals that save data from Dragon's Dogma will carry over, which means that it's likely an expansion pack (or DLC) and not a pure sequel. It's currently slated for Xbox 360 and PS3 in 2013, with more details to be released soon.