Microsoft's including search results for apps, including iPhone apps in its Bing search engine. The feature is called “auto app discovery” and it surfaces apps along with regular web queries. For example, a search for “Hotels in Mumbai” will pull up a section called “app results” which shows results like Expedia and TripAdvisor. You can also search specifically for “Top iPhone Apps” and “Download Fruit Ninja” and you'll find the apps.
Search results in Bing lead to iPhone apps
Bing will also help you directly download the app where if you perform a search on Bing on your phone, it will give you a link to download the app. Clicking that link will take you to the app in the App Store. If the app is already downloaded on your phone and the developer's integrated the launch functionality, Bing will launch the app on your phone. Apps like Facebook and Yelp can be launched directly from Bing. Some of these apps will launch within context, so if you search for “X-Men”, IMdB will open up to a results page for “X-Men”.