I would also argue that with iOS, they have the safest (big) mobile OS available as well. ASLR and DEP have long been implemented and with iOS 6 they are also i

I would also argue that with iOS, they have the safest (big) mobile OS available as well. ASLR and DEP have long been implemented and with iOS 6 they are also implementing Kernel ASLR. Almost everything is sandboxed and there are no known viruses out there (for devices that haven't been jailbroken). Jailbreaks are still possible (like you said nothing is perfectly secure), but have been slowed down to a point where hackers wait for a big OS release, before they decide to burn the exploits.