Apparently, if you set the iPad next to a Mac, your Mac cursor and keyboard just move between the Mac and iPad.
You can use a single mouse and keyboard between a Mac and an iPad.
Continuity: the thing that lets Apple devices share little pieces of data with each other. New: Universal Control
You can drag and drop files between Mac and iPad. It works "with more than two devices." We're moving a cursor from iMac to MacBook to iPad. And you can use any of the Mac input devices on any device.
Finally! You can just AirPlay to a Mac. This is how you can use a Mac as an external monitor now?
Shortcuts is coming to the Mac. Shortcuts in Finder, menu bar, spotlight, Siri.
Safari: Tab and window management. Cleaner toolbar. Tabs are more compact and they are shuffled up into the toolbar. And there are new tab groups. The tab bar and URL bar are combined. The search field is built into the tab. You can share an entire tab group in an email automatically. Tab groups sync to iPad automatically. On iPhone, the tab bar is on the bottom and it's very small most of the time, you tap it to hover.