Other new features in Safari 4 include Top Sites, giving users a visual preview of frequently visited pages; Full History Search, to search through titles, web addresses and the complete text of recently viewed pages; Cover Flow, to easily flip through web history or bookmarks; and Tabs on Top, to make tabbed browsing easier.
Safari 4 includes HTML 5 support for offline technologies so web-based applications can store information locally without an Internet connection. The browser also supports advanced CSS effects.
Safari 4 public beta is free and available now for download from Apple’s Web site.
Apple said Safari 4 for Mac OS X requires Mac OS X Leopard 10.5.6 and Security Update 2009-001 or Mac OS X Tiger 10.4.11, as well as a minimum of 256MB RAM.
Source : http://www.macworld.com/