During the Keynote Apple briefly touched on Spotlight integration for Apps on iOS. Turns out that the implementation is a lot richer:
Just this week, Apple unveiled iOS 9 with a slew of new features from news to multi-tasking to intelligence. However, one foundational piece of functionality was somewhat glanced over during the keynote —universal deep linking. In iOS 9, apps are cohesively linked together via deep links and the experience feels magical. - Medium
One thing I wonder about is how fast and how frequently they will index and update data.