There are moments in history that place one-to-many communications media in pivotal roles. These events ("Where were you when you heard...?") become elemental markers in history not just because of the enormity of what happened, but also because of how they were conveyed to the world.

You can't write the history of radio, for example, without mentioning Herb Morrison's eyewitness report of the Hindenburg disaster back in May 1937. It was a gripping broadcast of the fiery crash of a German zeppelin that took 36 lives. And don't forget Orson Welles' War of the Worlds program in October a year later. Its depiction of Martians marching on US cities panicked listeners, who thought the invasion was real and flooded police stations with calls for instructions or to report the odor of poisonous gas.

Television made its indelible mark in November 1963 when President John F. Kennedy was assassinated. Viewers watched spellbound, and heartbroken, while events unfolded -- from Walter Cronkite's tearful removal of his glasses while relating the news of JFK's death to John Kennedy Jr.'s poignant salute as his father's casket rolled past. And, it can be argued, TV helped heal that wound less than three months later, when The Ed Sullivan Show presented The Beatles' first US television appearance to 73 million viewers, many of them swooning or screaming in their living rooms as the quartet played "I Want to Hold Your Hand."

What will be the event that gives the iPhone its shining moment as a critical communications medium? If we consider the iPhone and devices like it as a new medium for communications, that moment will be an entirely new experience, one that embraces the video, voice and text capabilities of the iPhone. It won't have anything to do with watching YouTube reruns or sending mobile e-mail while on a bus.

Most important, given an iPhone's mobility, these future seminal events will affect people on the go. That is, crucial iPhone moments will be recognized because people will need to be out of their chairs and beyond their keyboards or TV remotes to become part of history. And just like the earlier examples from radio and TV, I believe there will be two types of history being made: a significant catastrophic event and a trivial, but arresting, piece of entertainment. Once those events happen, the iPhone will become more than just a useful tool or a fun device -- it will become part of who we are forever.

As with radio and TV, it may take a few years before the iPhone and its brethren have the critical mass to create a similarly widespread effect when pivotal events occur. You didn't have to be in Lakehurst to watch the hydrogen blimp disintegrate or in Dallas to see bullets rain down on the president's motorcade to feel the power of those moments. You simply needed a radio or a TV. For the iPhone moment, you'll need the device, but you needn't be present where history is happening.

And who knows what form that moment will take? An urban population dodging debris from a falling satellite? A frenzied group encountering a real Bigfoot? Your guess is as good as mine. But each event will require the shared use of the iPhone's mix of mobile communications features. One event will be terrifying, and one will be fun. And core to our social memory -- and the lasting history of the events -- will be the iPhone itself.