Wow. I'm normally not a big fan of SD art, but that's incredibly detailed and well done. I think that's a better representation of movie prime than any of the toys.
I almost want to say that it's Hidetsugu Yoshioka, who did the PD Type manga, or at least an homage to his work. Either way, it's very nice.
*stands up* Ahhh, one of my greatest pictures, that is. Yes, yes, I am the mysterious artist who drew that picture of.... *checks*.... Optimus Prime. I put a lot of time and effort into getting the details just right. I'm glad to see it has been received so warmly. Thank you all for your praise.