I don't think having something prepared is a bad thing so I would
encourage people to prepare things if they have something they really
want to talk about. I'm keen to hear a single point of view on some
topics especially at the beginning of each session as I find "I just
want to make this a dicussion" type sessions can easily turn into a
bit of an agree-fest.
In saying that however I think we could have had a little more
encouragement for some more open sessions - I know Ludwig was trying
to pre-organise a lot more as the numbers for barcamp keep going up
and it quite a big job to organise.
In any case these are unconferences so feel free to do what you want!
Glen