The first promo for X-Men: Days of Future Past has been rated in both 3D and 2D versions, each running 2m 15s. I’d image it’s the same trailer exactly but for the format.
Meanwhile, the the Captain America: The Winter Solider trailer has come in at 2m 23s. This one was certificated in 2D and unspecified-D, presumably 3D again.
Why are these trailers both gearing up for release now? Because Thor: The Dark World is on the way, so expect to see both trailers ready for roll out no later than when Thor lands on IMAX screens come November 30th.