It's ironic that only a few days after Facebook assured the world that it wasn't listening in to conversations, that a Instagram post from Mark Zuckerberg shows the web camera and audio ports are covered up with tape. This is interesting because Facebook has stated that it isn't using the device microphones to listen in on us: does Mark know something that we don't? Instead, rather than listening, are Facebook reading our lips? Or using the audio ports or vibration motors to listen in on us? This is a tongue-in-cheek jab, for sure, but Mark's image does highlight that concerns about privacy are taken seriously around the world. There is a legitimate threat: there are reports circulating the Internet showing how schools and government agencies are able to use our device's cameras to capture images or even video feeds without us knowing.
In the case of Facebook, the application and service is built around customers giving up personal information, which may be used to build an advertising profile. Facebook knows a lot about its users and the more we consciously use the service, the more it learns. In some cases, once we input data into the Facebook service, there is no way to remove it. However, the message to Facebook users across the world is mixed: Facebook would like it is more users picked up and used their live video feed services, as this is another way they can better understand us as consumers. However, if people copy Mark's actions and put tape over the web camera, it could stunt the adoption of the service. This does, however, feel unlikely: legions of Facebook customers use the service for its ability to connect with businesses and individuals all over the world, without considering the privacy implications.
Of course, the MacBook on Mark's desk is likely his work computer. Even given the open plan arrangement of the floor, it's likely that topics are discussed in the vicinity of the machine that would not be great to be shared around the world. It seems entirely plausible that Mark's personal technology has the cameras and audio ports uncovered and ready for his next live broadcast. It is not uncommon for corporate devices to have the camera disabled, but we don't see the current President of the United States of America with a spot of tape on the back of his Samsung Galaxy S4.