Notice the "iPhone" part is much brighter then that of the 3G, according to these pictures on Apple's site. I don't think there would be a difference in the pictures if there really wasn't some difference. Maybe they're using the same metallic looking finish as the Apple logo now?
Also, notice what I'm talking about in the new commercial too...
new 3GS
regular 3G

Also, notice what I'm talking about in the new commercial too...

new 3GS


regular 3G

