Quote Originally Posted by digitalron View Post
This is one of the the reason behind why Jobs wants Apple products to be a closed ecosystem: seeing how vulnerable the very configurable DOS/Windows environment is, he opted for a closed, secure, and consistent platform... which isn't a big deal for a majority of Apple's demographic target. Of course, it will always be a dynamic tension between those who want the "stability" that Apple provides, and the freedom (to use their devices as they please) that many techies demand.
Not sure I understood your post, but FWIW, the PDF vulnerability is already there even before performing the jailbreak. In fact, Comex exploited this back door and used it to gain access into iOS to perform the jailbreak.

Supposedly, Apple is working on iOS 4.3.4 to patch this up. But then, you'll lose the jailbreak. To patch the security flaw without having to resort to running the to-be-released iOS 4.3.4, you can run the "PDF Patcher 2" from Cydia.