Oh, I guess there's the experimentation angle. Can you transfer things you've made in creative mode to a server? See, I'd like that feature, but then I like playing where others are playing as it feels lonely otherwise. I have a feeling I'd get bore very quickly. I don't like playing SMP much as it is.
Speaking of Minecon. I'd hate to think that it would be similar to the official forums.
I've encountered some weird bugs today. How about this water floating in mid-air?
Or the squid that was becoming one with the cave? It was alive and it was moving its tendrils, but it was pretending to be a dirt block.