Apple clearly wants us all to treat devices and computers as interchangeable, so it's been building in all sorts of integration, such as iCloud Keychain, iCloud Documents, Photo Stream, Maps integration into Calendar, AirDrop, and now Bluetooth-enabled AirPlay (look, Ma: No network!), cross-device AirDrop, and Handoff.
It's also been making the visual experience more and more similar.
In a previous slide, you saw the iOS-like Today view in the Notification Center. The venerable Dock now has the iPad's look. Mac app icons now match the iOS versions. The system font has changed from Lucida Grande to iOS's Helvetica Neue. UI elements are simplified À la iOS. The iconography is also modeled after iOS, as the new iTunes 12 shown here demonstrates.