As an attendee, you don't think about this kind of stuff. But, like many things, you notice it when it doesn't work. For the full process, you need to grab Steve Cellini, who arranged PDC 2003 and PDC 2005.
But from the perspective of a person involved in a keynote, it's an impressive act of logistics. You probably don't think about it too much, but the demos you see at a PDC have been worked on for a long time -- often for weeks -- to make sure that they make their points clearly. All this while the demoers are working against early software builds that often don't work together well or break at random places. The boxes that the demos run on are shipped down a week prior to the PDC so they can be put into the backstage staging area -- the day 1 BillG/JimAll keynote setup had nearly 30 PCs backstage. The slides go into a team that works up to the last second so that they look good (thanks Mary!). And there are things you don't even think about -- the tables of food need to be set up and refreshed time and again. Over the course of the PDC, we're expecting, for example, our attendees to eat something like 2500 pounds of bananas.