i kinda figured you'd want to tackle that next so i played with some options... i'm going to assume that if you use a lambert you won't have to worry about specular anything, and it'll go from there to not without having to tweak anymore... i was using a blinn, and i found that although animating the eccentricity from 0.000 to the default value of .300 DID get rid of my specular highlights hanging out, the object went from no specular to super shiny (small, focused highlight) to kinda dull (larger, faded highlight)... if the animation from solid to transparent were short enough i don't think people would mind... or you could always try using that lambert shader instead