Via slashdot, directly quoted:

Harvard Law School Prof Jonathan Zittrain explains in The Personal Computer is Dead why you should be afraid — very afraid — of the snowballing replicability of the App Store Model. ‘If we allow ourselves to be lulled into satisfaction with walled gardens,’ warns Zittrain, ‘we’ll miss out on innovations to which the gardeners object, and we’ll set ourselves up for censorship of code and content that was previously impossible. We need some angry nerds.’
Slashdot

Zittrain completely misses the point. The open PC model works great for us programmers and geeks, but not for the 99.9% of computer users. This maximum majority has lived with Windows computers filled with crapware, malware posing as virus scanners, the terror of a single click giving up all their data to some hacker in Estonia, and having to rely on the neighborhood nerd to fix things, and they hate it. Absolutely despise it. The post-PC walled garden is perfect for them. They want email and internet and to use it without fear, risk and hassle. Which is why they are replacing PCs with iPads, iPhones and X-Boxes.

You are not your customer, Prof Zittrain.