Lifecasting (not to be confused with life casting, the art of casting sculptures from living models) isn't a new idea. Steve Mann, a Canadian computer scientist often described as "the world's first cyborg," began wearing a custom wireless webcam and sending periodic snapshots to his Web page in 1994. Jennifer Ringley started her "vanity cam" experiment, JenniCam, in 1996 and didn't turn off the cameras until 2003.

But live video streaming of the sort provided by Ustream and Veodia improves on traditional webcamming in several ways. For one thing, no special PC software is required. Users just connect their webcam or video camera to their computer, and Web-based programs take care of the rest. Video webcasters also get pages on the streaming services' websites where they can publicize their content, and they can embed a dedicated media player showing their webcasts in their own websites or blogs.

Just as important, live video streams can be combined in the same Web page with instant messaging or chat-room windows, enabling viewers to carry on conversations with each other and with the broadcaster. "The audience for Internet programming has really changed, and people are more interested in participating today," says Yeh. "We think that's an important part of the experience."

Lifecasting technology is far from perfect. Technical difficulties sometimes stop Kan from broadcasting. That's to be expected, considering that Kan frequently leaves his apartment and depends on a video camera, a microphone, a battery-powered laptop stowed in a backpack, four Sprint wireless cards, Sprint's own network, and complex Web-server software to broadcast his experiences back to viewers. But the goal at Justin.tv and Ustream is to automate at least part of this process so that the (literal) gearheads of tomorrow can simply don their lifecasting equipment and get on with their lives.

Will Justin or his successors become real-world Truman Burbanks, with millions of viewers? Probably not, as even video-streaming insiders admit. "It's unlikely that one person lifecasting 24-7 is ever going to compete with broadcast TV, in terms of reaching a broad market," says Yeh. "But that person may build up a very loyal core following. In just a couple of months, people really feel like they've developed a relationship with Justin. So this isn't just media- or hype-driven--it has an impact on people's lives."