Here's the full rundown from the Apple's WWDC which was held on 2/6/2014
- Safari has a sidebar bookmarks bar, reading list on the sidebar
- Safari has now deep twitter integration
- Push notifications from apps will push iOS alerts to your Mac. Notifications on the lockscreen. It will also do app updates in the background.
- No leather on the Calender app now
- New developer preview of Mavericks available now final release in Fall