What EuroPython 2011 and PyCon Italy Four did to avoid multiple meetings for rating talks is to setup a community voting system.

http://ep2011.europython.eu/blog/2011/04/11/talk-voting

All the early bird tickets are allowed to vote on the talk list so that we have a reasonable guarantee that we select talks that the community wants to see and that it's a conference tailored for our attendance. Writing the schedule still remains a multi-night work that requires a lot of flexibility also from the speakers themselves.