Sime,
I doubt we will be able to make it. I'm quite jealous of you! I would love to see the notes from your talk if they become available. It would be even better if you could post a link to them in the forums so people who ask us if e-commerce does this or that can have a place to start looking. We have been spending so much time working on Ubercart that we are not as up on ecommerce as we use to be. I have become very reluctant to answer questions since there has been so much development on ecommerce I am unaware of.
Have fun in Barcelona
Peace,
Andy