I would keep the dialogue to a minimum. as 
interesting as any cel lecture is, people begin 
squirming after about 20 minutes total of the cel 
panel because they just want to start swapping. 
I've seen groups of people leave the room once 
they get an idea that the speech part will be too 
lengthy, then they come back in an hour or so 
when they think it's "safe." I'll be speaking 
too, but will try to keep my stuff to about 5 
minutes. after we're done there will be plenty of 
time to talk the talk one-on-one. ^_^

/Mina