The key bit of information that was missed from the piece is that, I'm guessing, the iMac is linked up in mirror mode to the Thunderbolt display on the other pe

The key bit of information that was missed from the piece is that, I'm guessing, the iMac is linked up in mirror mode to the Thunderbolt display on the other person's desk... so they are each seeing the same thing on their own computer. From the photo it wasn't clear if one person had the iMac and the other had a MacBook plugged into the Thunderbolt display -- which left me wondering how they were actually pair-programming.