Conference Tools for Twitter

Recent experience of following (and contributing to) Twitter stream at the annual meetings of the American Sociological Association inspired a number of ideas (not all original, I'm sure, and some probably already implemented) in connection with Twitter and conferences:

1. Conference organizers should devise and disseminate a simple hashtag schemes for sessions/presentations.
2. Set up scheduled tweets that announce sessions, say, 15 minutes ahead of time.  Tweet can contain a link to web page with detailed information about session.
3. Presenters can submit brief, say 5 to 10,  tweet summary of the points they are making and these can be automatically scheduled to be tweeted during the talk.
4. If talks are being live streamed, start of each talk can be marked by a tweet with URL to the stream.  Major point tweets could be synced to location in recorded video/audio.
5. Develop an app that aggregates and archives live tweets of presentations for live and followup discussion.

What would you add?