In previous versions of Safari, running downloads popped up in a disembodied Downloads window that tends to get lost behind your open browser windows.
In Safari 5.1, though, the second a download starts, a little icon pops up next to the search bar. Clicking on this icon reveals a very iOS-like drop down window of past and current downloads. Clicking on a download opens it, while clicking the magnifying class locates it in Finder.
While we are unsure if this is really a novelty we still think it is pretty cool!