It's only mentioned briefly in the blog post, but one of the biggest wins with this system (and the aspect that I absolutely love when using it internally at Google) is the simplicity of screen sharing into a meeting. Anyone who wants to present can simply join the hangout from their laptop and then share their screen. Not only does it mean you don't have to fuss with cables/adapters (which can also break/wear out), it also means that if someone wants to share something while someone else is presenting, you don't have to disconnect and reconnect various computers; the other person just shares their screen as well (and/or the first temporarily stops sharing their screen). It also means you don't have to have dedicated rooms for presenters - someone in a remote office can present from their laptop to a meeting room elsewhere.

Having a meeting that doesn't involve slides? The meeting organizer can just throw up the meeting agenda with a click or two - or if it's in something like a Google Doc, the meeting agenda can even be dynamic, with people adding topics they want to visit as they determine them, and the organizer simply working their way down the agenda as it grows. Add the agenda as an attachment to the google calendar entry for the meeting and people can review/add to the agenda ahead of time, and then look back at it after the meeting for a reminder of what was covered.