dizzyj:

...An open platform is going to draw virii, spyware, and every other bad thing that can ruin using a laptop or desktop computer. Having a gatekeeper to ensure that applications aren't malware is a good thing, even if it slows innovation a bit. ....

I see what you're getting at: closed platforms are harder to write code for (or against). But harder does not mean impossible. And I don't think Apple's control of what gets put in the store means they necessarily do much testing on the apps. I certainly don't expect the apps I install on my iphone to have undergone a rigorous testing process by Apple.

I think in general closed platforms delay the reporting of vulnerabilities (which is quite different than the existence or exploitation of those vulnerabilities). This hurts the good guys much more than it hurts the bad guys.