Google Now is one of the best features of Android Jellybean. The service enables you to ask questions and it'll try to answer them as best as possible. It's very quick, quicker than you would expect. It is Google's answer to Apple's Siri, but a little better and quicker. It also doesn't talk back, like Siri.
Google have just updated their iOS search app to include the voice functionality you would find in Google Now. You can now ask questions like what's the weather like in any area, what is a hippo and many other questions. It'll then directly answer them via voice and give you concise information about what you were searching for.
The only thing missing the actual cards feature which Android's Google Now has. Also because it's not fully integrated like on Android you won't be able to launch apps and use things like the navigation apps. This is where of course Android has a huge edge. This also means that it'll never be as good on iOS. However the ability to search has now become a very quick affair, why type with that small keyboard when you can simply speak.