This is something I missed about a month ago. I had several people asking me about March 30th, 2008 being the 150th anniversary of the invention of the pencil. I was telling them the wood cased pencil was much older and that they must be mistaken. It appears they were refering to the 150th anniversary of the Hymen Lipman patent which actually was for a specific design to encase an eraser in the opposite end of the pencil from the writing end. Either end could be sharpened.

Hyman Lipman Patent Drawing

This post from Today in Technology History covers more details on the history. As it turns out there were countering claims from another inventor who developed the use of a ferrule to attach an eraser (as per today's common method) and with Faber who claimed these were not patentable innovations since pencil and erasers previously existed and the combination did not change the basic function of these two items. The case eventually went to the US Supreme Court.