This is just old fashioned telephone conferencing. Dial a number, enter a conference code. Uberconference has screen sharing, dial-out vs dial-in, etc.

The open source part of this seems nice, as opposed to figuring it out yourself with Twilio. They have it all packaged to run on Google App Engine. Though the timing isn't great now that Twilio supports their own "serverless hosting" via AWS Lambda. They should probably offer an option to deploy it that way as well.

This isn't earth shaking to me, but there are companies that still do a fair amount of plain old telephone conferences, and overpay for it.