The top level commenter was not talking about an optical drive like CDs or DVDs, they were talking about having optical audio connectivity through a TOSLINK mini plug.
Ah. I used to plug my old original Core 2 Duo MBP into a 5.1 system using a mini TOSlink cable, but since HDMI started doing surround audio I haven't had a need for optical audio connections. It was cool seeing a LED inside the audio jack, however.