I'm glad you brought this up, because I was happy to see that feature announced a couple weeks ago. However, I have not noticed any apparent change to what I already see.
Where you seeing these leaves? Do they show up on your AncestryDNA Member Match list? This is what would be most useful.
I have two members that show a Shared Ancestor Hint after I click on their name, but it doesn't look any different than it did before. It shows each of our partial trees and our common ancestor. I wouldn't have known that unless I clicked on their name. There were, and still are, no leaves.
What would really be useful is to have the leaves show up on the long list of members rather than requiring us to click on each one to see that Shared Ancestor Hint.