I too agree

, but it's not an absolute truth to say that all IOS protection is before the event. Significant known exploitable code exists in all current versions of stock IOS (5.1.1), and many previous ones too. These are the very same userland exploits which are used to jailbreak the device. They could equally well be used by any malicious code writer since all the exploits are freely available and fully documented in the public domain. I'm not saying those exploits would be easy to use maliciously, but I can conceive of scenarios where it is possible.
Similarly, malicious jailbreak apps (not that any exist to my knowledge) are / would be difficult to get into the public domain to a large number of owners. There is probably just as much chance of a malicious app store app getting through the Apple approval process, and that is a far more enticing target for a truly malicious h4x0r.
There is no right or wrong answer in this debate, but I do always push back against the misguided generalisation that jailbreaking IOS somehow makes it significantly more likely that a user is exposed to viruses or malicious attacks by default... there is simply no evidence to support it, and I've been passionately jailbreaking Apple devices for over 5 years now. During that time there have been, if I recall correctly, just 2 potential "virus like" threats to IOS, one specific to jailbreaking which was never anything more than a proof of concept, and another which was valid to both stock and jailbroken devices (using the Safari PDF font exploit). But no malicious code was ever discovered in the public domain relating to either of these as far as I can remember, and the jailbreak community patched the second exploit in less than 24 hours, with Apple following suit on stock devices another 24 hours later

Yes, if jailbreakers do silly things like enable SSH, fail to change the password from the default, connect to a public wifi network with an unsecured router, and have the very bad luck to encounter a malicious user on the same network who is specifically looking for folks like them, then potentially they could get into trouble. But that same malicious user is probably doing much more interesting malicious things on the network like trying to intercept unsecured data from EVERYONE on the network, rather than looking for a careless iDevice jailbreaker
With a little bit of care, common sense, and research, both stock and jailbroken iDevice owners should be equally secure in my own humble opinion