Rephrased
"Any designer of new features and systems needs to answer the question, 'What did Linux Security Modules do?'
Jon Callas, who as co-founder and chief technologist of PGP helped bring strong encryption to the masses, has taken a job with Apple working on operating-system security. His move around the beginning of the year was confirmed by two of his long-time friends and this brief bio, which says Callas remains on PGP's technical …
... Linux security guys first looked at what MULTIX and VMS did. Whether they improved on these models or just mitigated structural issues is open to discussion (most *BSD people, for example, would tell you that the Linux security model sucks moose balls. Most VMS people would probably not even utter the words "Linux" and "security" in the same sentence without washing their mouth with black soap immediately afterwards. But IT is all about making exactly the right amount of compromise. Or so I've been told.).
Good news for the Church of Jobs anyway. With the usual reservation: you can have all the security experts you want, it won't help you the least if their choices are overridden by the marketting dept. (see MS history for proof).
>I suppose that he will work on MacOS and on the iPhone (and iPad) to make them even harder do crack/copy/alter/install on another device.
Doubt it, why take on a job that you could only fail at? More likely they're sick of being first to fall in pwn2owns and also battening down prior to the inevitable onslaught of iPhone malware.