Google Now comes to iOS in new Search app update
Not surprisingly, because of the 3rd party limitations on apps in iOS, Google Now doesn't get a system-wide launch shortcut, or the same full background syncing (although it can monitor your location.) The app also will not push notifications through the iOS system, and it can't pull information from your local calendar, it only pulls from Google Calendar.
Oddly though, there are some cards that aren't available on iOS either. At launch, only 22 of the 29 different information cards have made the trip from Android to iOS. Cards that are notably missing are airline boarding passes, Fandango movie tickets, and local events.
Still, even with these limitations, Google Now is one of the best pieces of software around, and proves just how much value can come from a company using our personal data to give back to us, rather than just sell more ads. If you want to try out Google Now for iOS, the updated Google Search app is available for free in the iTunes App Store.