Searching for productive co-opetition; also see Facebook Now Using Google App Indexing To Drive Visitors From Search Into Its App (Search Engine Land)
"Google can’t show content shared through logged-in and private Facebook app sessions, meaning it is still locked out of most information inside the walled garden of Facebook’s social network. For those searches, users will have to use Facebook’s search service, which it recently updated.Google Gets Surprise Ally in Mobile-App Search Push: Facebook - Digits - WSJ
However, Facebook’s cooperation is a sign that Google is making inroads in confronting a big challenge – searching inside apps. Google’s search engine is dominant on the Web, but its computers can’t automatically “crawl” and categorize the information inside apps, where smartphone users spend the majority of their time. So it must persuade app developers to let it peer inside."