Deciding you want to live stream a conference is one thing, but actually figuring out what to use to do it is another. I was recently tasked with helping with such a goal and in the process analyzed a huge amount of software and platforms. We were looking for a very specific setup (two way feed + PowerPoint + chat) and each available platform offered something different. To stay organized, I created a chart breaking down the specs of our various options. I analyzed offerings like UStream, GoToMeeting, Webex, Skype and Vokle, and laid out which access applications, offer a mode for feedback, require registration etc.
Take a look at the chart, available here, and hopefully it can be a resource for you if you’re ever tackling a similar project.
As Media Changes 
Great chart, will save me much time. Thanks!
I was one of the presenters at the conference Seth alludes to, and I had been wondering about what went into the selection of the product we ultimately wound up using! Thanks for sharing your insights here, Seth!