If developer of the iPhone app WhereTo is to be believed, Apple is now field testing iOS 5 on its devices and running real App Store apps on it for testing purposes. iOS app developer FutureTap tweeted from their account that they have received the first iOS 5.0 crash report. The application crashed on iOS 5 due to the MKUserLocationBreadCrumb, that is an API related to the iOS maps and location functionality.
Just received the first iOS 5.0 crash report. MKUserLocationBreadCrumb sounds interesting.
Apple is going to officially announce iOS 5 in its WWDC event this June, and this testing stuff makes sense because the event is not very far away and because Apple is expected to handover their latest iOS version to developers right after the event.