Hard to say...
The lighting conditions are very different that when Marcia's picture was taken. That might explain at least some of the appearent difference in color. I've seen very significant apparent differences of color for things like Pikes Peak and Garden of the Gods during the course of a day. The same thing may be happening with the ET.
It's also possible they've switched colors for the spray on insulation. The tank doesn't look any different in size to me. There's a seam that goes around the ET that appears to be just above the Shuttle's nose in both pictures.