Safari 4 Beta is available for download here.
Safari 4.0 Beta is for both Windows and Mac. The new features are many, including Top Sites, which provides easy access to your most visited sites. Cover Flow from iTunes is added for your history or bookmarks. Tabs are now on top ala Chrome. This takes a bit of getting used to.
Safari 4.0 Beta does seem faster and the screen is larger with the tabs on top.
This Beta is ready for you to try. See if you find the new features useful. Warning: some of your 3rd party plugins, etc. may not yet be updated.