As expected, Siri is coming to the Mac. Siri will be able to search for files, and refine those searches by indicate specific apps and people related to the files.
Copy it on your iPhone, paste it on your Mac. And vice versa.
Every app, including third-party apps, will be able to have multiple tabs. That means Map tabs, Twitter tabs, any kind of tabs you can think of. (And there's no optimization needed by the third-party developers.)
iPhones will gain the ability to unlock your Mac when you get close to it—this serves as a double-edged sword for security. Since you don't have to regularly enter your password, you could choose one that's more complex, but if your phone and laptop are both stolen, the thief has a key.