Craig Federighi, Apple's SVP of Mac demonstrated the all new Safari during the WWDC12 keynote today in San Francisco.
Safari has always been intertwined in the Mac OS - but it brings even more functionality in Mountain Lion.
Safari Unified Search
Just type a few characters into the unified smart search field. Mountain Lion Searches matches in both your bookmarks and browsing history.
If you were browsing on another device - there is a new feature called iCloud tabs - which lists all the pages you have open across all your other devices.
The beauty of this is that you can pick up browsing right where you left off.