[RowdyScot]

Notch was with Machinima most of the day doing live streams and playing while answering questions.

CONFIRMED:
Stained glass
Horses
Gates (for fences)
Floodgates
Diving suits
Alternate types of clothing instead of just armor
Furniture
Redstone light sensors
Backpacks
Fireworks (including random error factor of shooting off in random direction)

POSSIBLE:
Mirrors
Skinnable Statues (yay!)
Colored light...possibly applied through stained glass, possibly not

As always, it remains to be seen as to when these things will happen, but Notch confirmed that gates and diving suits are coming sooner than anything else on that list, with horses as soon as they can be coded properly.