It would be great if we could report crashes that happen during CI runs as part of the automation results.
For Simulator:
App crashes will be generated within /Library/Logs/DiagnosticReports/. Also, the output from "/Library/Logs/iOS Simulator//system.log" (7.x) or "/var/log/system.log" (6.x) sometimes contains a more interesting stack trace after symbolicating. It generally comes directly after "Terminating app due to uncaught exception".
For Devices:
If Xcode can pull logs and crash files off of devices, I'd assume the same should be possible from command line (maybe requires using libimobiledevice). I haven't tried this before, but I'd hope this could be possible.