Ustream.tv allows anyone with a camera and an Internet connection to broadcast a live stream. The streams on the website range from live coverage of concerts and political events to inane broadcasts by random people talking to the camera on their computer.
Ustream will be streaming the Barack Obama inauguration today on this page. Until last night, that information would be useless for iPhone users, but last night Ustream announced that Apple finally added to iTunes the Ustream app -- just in time for the inauguration. So now, YES WE CAN view the live stream on our iPhones.
The Ustream Viewing Application doesn't let you send video out to the world from your iPhone. It is just a viewer app that allows you to watch any live or archived stream on Ustream.com on your iPhone. You can also view and participate in a live text chat, which appears just below the video. Note that Ustream sends a lot of data, and thus it requires a WiFi connection. 3G is not sufficient. You can download the Ustream app for free on iTunes here: 
Here are my quick observations after my (very brief) testing of the app so far. First, the audio seems to stream very well, but the video often gets choppy. Second, the app is a little buggy and does crash. You can minimize those crashes by first turning off your iPhone (hold down the button at the top) and restarting your iPhone before using the app. Third, you can turn your iPhone sideways to get a bigger picture. Final observation: how cool is it that you can watch live streaming video on your iPhone? I noted the other day that Sling will soon allow you to stream your live TV to your iPhone, but that app won't be out for a few months. Ustream is the first to bring live video to the iPhone.
Here is what the Ustream app looks like when I was viewing the archive of Obama's acceptance speech Monday night. The quality of a still frame of video doesn't look that great, but when the video is playing it is very watchable.
Thus, if you want to watch Barack Obama being sworn in live as it happens on this incredibly historic day, but you don't happen to be near a TV, just download the Ustream app to your iPhone and stay close to a WiFi connection.
By the way, the 20th Amendment to the U.S. Constitution provides: "The terms of the President and Vice President shall end at noon on the 20th day of January ... and the terms of their successors shall then begin." Thus, the swearing in ceremony is at Noon Eastern time today.
