Any engineer or systems designer has likely experienced the type of situation during a serious brainstorming session which breeds a tangent so extreme and so off-topic that all notion of the original conversation is lost.
Conversations about server farm load-balancing or circuit architecture turn to the likes of imaginary systems and interdependencies between a Brittany Spear's Prius powered time-machine which is used to create crop circles through the guidance of NRO satellites, and fully funded by the cybernetics research group at NASCAR.
These imaginary journeys, and the elaborate plans that are created, provide momentary relief from the more daunting and serious task at hand, allowing for the small group gathered late at night around a work table and whiteboard to re-focus and re-energize during moments of frustration.
So, it would only be appropriate that Google is now famous for its whiteboard which now contains the truth about their master plan to take over the world. With capabilities that range from orbital mind control to centralized P2P networks, and milestones like the elimination of evil, it is no wonder they have grown so quickly.
This ever-evolving mainstay of Google was likely created out the above situation, with no serious intention for persistence or long-term evolution; however like everything else with Google, it has become a major hit and fan favorite.