To be honest in the earlier pictures the fingers were just roughly placed to resemble holding a phone and so weren't getting lit properly. In this pic I've adjusted the fingers so that they are touching the screen this time (like somebody would in reality) and so there is more illumination of the fingers this time.

Just for fun I also rendered it in PoserPro2012 after EZSkinning the figure and using SSS in the render to compare the difference available in PPro2012 to PPro2010. Click it to see it a bit bigger.