Previous non-starters include Knocking Live Video which streams video from one iPhone to another, P2P style, but can't broadcast audio. The other is Qik which streams video to multiple clients but doesn't stream live. It should be noted that the jailbroken version of Qik includes live broadcasting.
Ustream Live Broadcaster changes all that and allows live broadcast of audio and video from the iPhone. And it's free!
Broadcast live to your Ustream Show from your iPhone, Nokia or Android phone with the Ustream Broadcaster Application. Easily stream live moments from your phone and share with your friends, family, fans, followers and others -- and have the recording of your video afterward! Interact with your viewers during your broadcast using chat or Ustream's Social Stream, which integrates a live feed of Twitter, Facebook, MySpace and AIM messages and send status updates to Twitter and Ustream.
The Ustream Broadcaster looks to be a killer app for live broadcasts of things like conferences and concerts - just remember to turn off the iPhone's auto-lock before rolling.
Now all I need is a decent iPhone tripod, if you've got one post it in the TalkBack.