What's your guess on what Yoshi's taunts will be? I think he'll probably keep the N64/Melee one. I actually think this picture is part of that taunt:
Also, the double spin he does in the E4all trailer will be one too. Also shown in a non-taunting update, but in Yoshi's FS update (I think):
Edit; this may be his 3rd taunt:
Alright, I've learned something. Most of the stuff we don't know about has been in certain pictures or trailers in the dojo already, like Wario's B and Up B. If we dissect that last picture, we may find out if it really is or isn't Yoshi's mysterious 3rd taunt.
First of all, it seems that DK is attempting to push the slanted part of the bottom block, so that's an impassable wall. If Yoshi is indeed in his about-to-fall animation, then he would have to be on the edge of a platform. What's confusing is that there is a very narrow space between the platform he is seemingly on and part of the impassable structure DK is pushing on. The narrow space may be an actual space you can fall through or may just be the quickly-drawn feel Sakurai wanted this certain part of Pictochat to have.
Another analysis we can make is that Bowser is jumping, but where did he jump from? He seems to have jumped from the platform right under him, or might've jumped from the one next to Yoshi. He looks like he's preforming his aerial forward move, so that should take him some time, so that increases the chance that he jumped from the solid platform next to Yoshi.
Also, with
http://youtube.com/watch?v=U9ImoT_LOdI that video, at around 3 minutes, I've observed the Yoshi taunt in question and matched them. Yoshi's Story Yoshi tils his head back more, grabs his hands, and tip-toes with both feet. Things the Brawl Yoshi isn't doing in this picture. *It may be just the startup, though*
So, in conclusion, there are 2 likely outcomes.
A. This picture contains Yoshi's about-to-fall animation. (most likely)
or
B. This picture contains Yoshi's 3rd taunt, the All-Fruit Yoshi's Story taunt. (I wouldn't count on it)