Here are some new features you will find in safari 4
Top Sites for Safari 4 is what Speed Dial is for Opera and Firefox, but is done more aesthetically. Top Sites gives you a stunning at-a-glance preview of your favorite websites whenever you open a new tab. You can add up to 24 thumbnails and even customize the display by pinning a favorite site to a specific location in the grid.
Sites that have their content updated are reflected in Top Sites by displaying a star in the upper-right corner of the thumbnail.
Cover Flow offers a highly visual way of reviewing your site history and bookmarked sites, presenting full-page previews of the websites. Directional arrows let you browse forward and back or you can quickly flip through multiple sites using the slider.
Full History Search, where users search through titles, web addresses and the complete text of recently viewed pages to easily return to sites they’ve seen before
Safari 4 now places tabs on top – a feature borrowed from Google Chrome. You can also rearrange tabs by simple drag and drop. Unfortunately, this feature is broken in Windows and it messes up the title bar and minimize/maximize/close buttons.
Safari 4 also features Smart Address Field, that automatically completes web addresses by displaying an easy-to-read list of suggestions from Top Sites, bookmarks and browsing history. (Opera and Firefox 3 has this already)
The Smart Search Field, provides users with recommendations from Google Suggest or a list of recent searches to make searching easier.
Full-Page Zoom allows you to zoom the full page, not only the text. Safari scales images and graphics as you zoom in and keeps text razor sharp while preserving the page layout.
Checkout their blog announcement for more information.