Google Now is a critical selling feature of Android, and to bring it to iOS seems like Google is shooting themselves in the foot. But their revenue strategy relies upon having products on as many platforms as possible, which is why this makes sense. Google is also probably betting on the halo effect to bring more customers to Android.
The product still gives me the creeps, though. Even though it’s automated, something rifling through my email, contacts, and calendar to try to predict what information I’m going to need is unnerving.