An iPad is not in danger of replacing my PC, I completely agree with Apple's proposition that it's a third class of devices.

I won't program on an iPad. I like the look of iWork, but I can't see myself composing my next presentation on it. I won't be (legally in Canada) ripping my DVD collection on it. I might write comments like this on it, but without a stylus I can't see myself writing a blog post on it.

An iPad may replace my mother's Macbook. And it ought to. She surfs the net, writes email, does her banking, and skypes. She has no need of a device that she can tinker with.

I see iPads as a threat to books and also as a threat to secondary televisions. The big screen isn't going away, but a lot of people like a smaller TV in their bedroom or kitchen. Being able to watch movies and favourite shows on a small device may displace these extra televisions.