Browser tabs across the cloud
Here's a feature that debuted in OS X before iOS: In Mountain Lion, a new iCloud Tabs popover in Safari 6.0 lets you access recently and currently open browser tabs in any Mac that has the same Apple ID, so you can pick up where you left off as you move from machine to machine. When iOS 6 ships this fall, its Safari browser will also participate, so your iCloud tabs will work across iOS and OS X.
Safari 6.0 also unifies the address (URL) and search bars, à la Google Chrome, so searching and entering URLs are now the same thing. As you type in Address and Search bar, suggested sites display below it.