With the toolbar hidden and icons shrunk down a bit, the Mac OS X Finder doesn't look that different from today's Finder. In the top left corner, you can see the red-yellow-green button combination (close-minimize-maximize). In the top right, there's no button -- a space formerly occupied by "single-window mode," an innovation Apple was toying with that's been dropped from the public beta.
The second row of the Finder bar contains the name of the folder you're looking at. To the left of that is a back button, allowing you to go back to the previous folder you were viewing through this Finder window. (Note that there's no forward button, so going back is a one-way trip.) To the right are three buttons that let you toggle views for your folder. From left to right, they're: icon view, list view, and column view.