PAX Mojang booth report:
Endermen are scarier than they looked in pictures. If you aggro one, it will slowly begin moving towards you, unless you look away, in which case it will teleport and speed up. Running is a bad idea. Presumably it will start hitting you if you sit and stare at it long enough for it to reach you. Haven't seen any drops. They burn in the sunlight. You will only ever aggro one at a time, the entire group will not start moving at you once you piss off one.
You now have to draw your bow, length of draw probably affects the arrow's distance flown but haven't tested.
World gen is more awesome (sweet floating islands(unless it was a fluke))
Title screen changed to something similar to Aether's title screen, slowly pans around a map (probably last one played)
Chunks appear to be cubes now, but not sure (That's how it looked when Jens was flying around in creative mode.)
Everything looked great ingame, but I was at an over-the-shoulder perspective and any number of things could have caused that.
Post things you want more information on within the next 7 hours (leaving at 9:30 AM PST) and I'll keep them in mind when I get to the booth again. I haven't actually played 1.8 yet, so take everything here with a pinch of salt or two. Also, I haven't slept in the past 29 hours, so my apologies for weird wording, grammar, and what have you. Will edit with further information in ~24 hours when I return.