The number is already outdated as I write it, but Apple said this morning that more than 11 million copies of Safari 4 have been downloaded in the first three days of its release.
That includes 6 million copies of Safari for Windows, which should be a wake-up call to Microsoft about improving Internet Explorer.
Safari 4 also has new features like Top Sites (which previews frequently visited or favorite web pages), Full History Search (which lets you quickly rotate through your previously visited pages), and Cover Flow, the side-scrolling view borrowed from iTunes. Safari is based on the open source Webkit browser engine. Apple says Safari is the first browser to pass the Web Standards Project’s Acid3 test, which examines how compatible the browser is with dynamic web applications.