Yeah, Chewie does seem a bit small (or other wookiees a tad big). I remember on one of the ROTS "web docs" on Hyperspace, they talked about Chewie is "just a little kid" I believe as Rob Coleman put it, when he was explaining the upcoming scene to the other wookiees. I guess that could be why the others seem a bit bigger, but from the pictures I've seen, the size difference isn't that big (between wookiees) in the movie, although the figures look like a different case. It would be interesting to see the ROTS Chewie next to the ROTS Tarfful figures and see if there is that much difference. I don't mind Tarfful, or other wookiees, being taller than Chewie, but they are just all around much, much bigger.
I agree with you about that pic too Mikey. I really like that pic, and think its cool, but Yoda shouldn't even be knee high on the wookiees, should he? As small as he was next to Luke, I would think the furballs would tower over him. Boy I feel like a nerd right now, complaining that "the scale between Yoda and the wookiees isn't nearly accurate enough" (pushes up glasses).
Anyways, hopefully it will look good on screen.