Looks like IGN got some exclusive pictures today (only 3 though). There is one of interest for this thread, too:
Looks like these guys are charging up their smashes. And this picture gives me more evidence for a theory I've had for a little while. Check out Link's stance in that picture. Now look at Link's stance in this one:
See that he is in the same stance, but much lower? I've also see him pull off his F smash in the video, and I coincidentally paused it on the frame where it flashes as he does the attack. His stance was much higher, like the first picture.
What I think is that the characters may be moving while charging their smashes. For example, Link holds his sword up high when you start to charge the attack, but he slowly goes down into a lower position the longer you hold it. Basically, it doesn't affect gameplay much (outside of letting other people know how long you've charged a smash for) but it is definitely aesthetically pleasing.
Of course, I could be wrong, and it is simply the angle that is making link look like he is lower. But I guess we wont know for awhile, eh?