Ask HN: Best way to do a screenshare with 50 people?

I'm running a sales presentation tomorrow where folks are going to watch a Power Point demo remotely. We've been using Adobe's ConnectNow product for these and it works pretty well. But it has a 20-person ceiling.

Just found out tomorrow's call is going to have 40 (!) people on it.

Adobe's got a crazy expensive thing that takes 3 days to provision. Webex is telling me the same story.

Anyone have a better way to do this?