At first glance, ustream.tv looks like another way to stream a live webcam. Look a little deeper and you'll see that they're changing the live broadcast model.
I was introduced to ustream.tv while listening to a podcast called net@nite with Leo Laporte and Amber MacArthur. They mentioned a live video feed, and that feed was done with ustream.
At the time (April 07) ustream.tv wasn't able to keep up with the traffic demands that a Leo Laporte required. Now they've grown and scaled to handle that and more.
As an example, former TechTV show host Chris Pirillo has a live (sponsored) feed from his office. Though the largest number of simultaneous viewers I've personally seen there is tiny (70), they claim they're ready for Leo.
The fact that this company exists was inevitable, but that they started the company in February of this year is nothing short of amazing. Talk about a zero to 60 entrepreneurial experience.
With the new version about ship, I'm positive they're going to play a major role in redefining what live broadcasting is and who has access to it. Their features are geared toward monetizing live video streams and the subsequent archives. Incredibly cool.
Watch for ustream.tv.