(Lots of pictures; not for those on dial-up.)

http://massiveblack.com/MBwebolution/blog/?p=301

Interesting - Sentinel Prime's shield was designed for Optimus, Igor was originally Undermine and Que was originally Steeljaw. Also, I just noticed that Shockwave's Driller (originally Colossus) has three crushing gears kind of like the ones on Shockwave's back.