So I finally got around to taking screenshots of my Powerbook G4's operating system, 10.5 "Leopard".
Click on the thumbnails to see the screenshot.

This is the default desktop. Plus a folder and a mounted drive.

The first thing that you will notice is the significant facelift. No more pinstripes, or the brushed metal effect from 10.4 for that matter, anywhere. The dock now also has a 3D effect to it. Complete with reflections!
The Finder has been modified a bit as well. All the icons in the Sidebar are now organized into collapsible groups. They're also trying to push their iDisk service pretty hard because there's an icon displayed front and center for it in the sidebar.

Like previous versions, the Finder can show you files in list, icon, or column mode. However, 10.5 adds this new mode as well (which is in a basic sense a ripped-off idea from Windows XP nearly 6 years prior).

"CoverFlow" as it is called displays previews of certain document types (notably photos and videos, as well as PDFs) that fly about in 3D as you scroll through them, like a book. They can also be dragged around like regular icons. Some video formats can also be played straight through their "cover".

Except for folders filled with photos and videos, I don't see the utility.

Here's yet another new feature. "Stacks" allows you to quickly browse folders that you put in the dock. Click on it, and up pops the files in a "fan" as shown, or in a grid if there are alot of files.

One crippling limitation is that sub-folders cannot be browsed this way.

"Spaces" is Apple's new stylish multiple desktop feature. You can add "virtual desktops" in addition to the four you get by default, and you can drag programs between them too.

A whole bunch of bundled applications.