Samsung has posted a teaser video, see below, for the American version of the Galaxy S II. Removing any doubt that the August 29 event is for the new phone, the clip also briefly shows what one of the new versions will look like.
No carrier badge is visible, though the design looks more likely to be the Epic Touch 4G for Sprint rather than a visible change like the Hercules coming to T-Mobile.
The change was expected given the original Galaxy S having followed a similar control scheme rework when it launched last year. R