I'm one of the ones who watched the keynote, knew about the feature - and I still couldn't do it. Specifically the three finger "unpinch." However, this thread

I'm one of the ones who watched the keynote, knew about the feature - and I still couldn't do it. Specifically the three finger "unpinch." However, this thread prompted me to retry, during which I realized it was a lot easier if I used two hands. We'll see if I can manage to use it regularly.