And while we're comparing Safari 4 to its beta, I had also noticed various progress bars that were available in the beta. The final release has gone with none of them, choosing instead a more radically visible indicator:
My immediate reaction is that I preferred the subtlety of the beta indicator (eventually preferring it to the Safari 3 one), but it's not a bad choice. In the Windows version of Safari, however, I think that the indicator is too bold (it has a darker color than on a Mac) and appears to float above the address bar rather than nestle inside it.
The other big change is that the tabs have moved back down below the address bar, a la Safari 3. Their temporary displacement in the beta was most likely a response to Chrome's tab placement. One strange side effect is that the tabs appear to run into the address bar, rather than the page itself: