Recently (May 2012) I visited Lego Discovery Center in Duisburg, Germany. For grown ups, there were many fun details made out of Legos and this huge Einstein face was one of them. The Einstein was made completely out of Lego bricks and the motorized eyes were moving slowly from side to side.
I have seen images from other Lego Discovery Centers, and it seems that this kind of Einstein face is quite common in these Lego attractions. I guess someone has either made the instructions for building Einstein (with how many steps?!) or somewhere is a person or persons who have been building these faces for years! :)