I'm kind of surprised Black Panther is on Iron Man's side, as in the comics, this is what happened when Iron Man tried to get Black Panther on his side.
^^Oooooooh. Rewatching the trailer, that's T'challa lying on the ground when that building gets blown up 41-42 seconds into the trailer. I'm guessing that's a summit of all the world's leaders meeting to discuss/ratify the Superhero Registration Act, and that's why Black Panther is on the pro-registration side. I'd guess that Ross frames Bucky for blowing up the building, as opposed to my earlier theory about Iron Man finding out Bucky killed his parents?
*edit*
Although Fadaar brings up a good point in IRC. How the fuck does Cap's shield bounce? Wouldn't it just hit something and immediately fall to the ground instead of bouncing away?