In Pictures: OS X Mountain Lion arrives - the top ...
Copy status at a glance
Here's one of those subtle changes Apple is famous for: When you copy or download a file, its icon has a progress bar so that you know how it's going.
That's more elegant than the floating Copy panel Apple has long used in OS X. But that Copy panel still appears when you copy multiple items, so you can see all their progress in one glance, as well as when a copy operation takes more than about 10 seconds. Still, if the Copy panel is obscured, you see the progress bar in your Finder window (and vice versa).
In Pictures: OS X Mountain Lion arrives - the top 25 features