I think the rules for this debate are pretty strict... each candidate can't ask the other one questions - and isn't that a big part of what a debate is? I think this will mostly just be like Bush and Kerry happening to be giving speeches in the same room.
I dunno about anyone else, but I found it funny during the 2000 debates funny from all of Gore's sighing and whatnot.
And I guess that's why they imposed strict rules this time around.