What I expected to happen was..:
Leaves to be named 'Birch Leaves' or 'Oak Leaves' etc.
What actually happened was...:
Leaves are named 'big_oak.big_oak.name.name' or 'birch.birch.name.name'.
Steps to Reproduce:
Click on the leaves in creative menu or gather leaves. with Shears.
Affortunately this was reported so many times in the G+ community, as the spawn eggs, and it will be fixed in beta build 6.