Interesting post by Andrew, and he's spot on - but with the perspective of an eReader. Which really just raises the question: Is the iPad an eReader?
Personally, I think it's not. It's certainly a better eReader than my laptop - great. Is it better than a typical eInk device? Well, that certainly depends on whether you need WiFi access, color, and quick response, versus daylight reading, easy on the eyes, and a more integrated book experience.
I think the great diversity of choices will help each company to strive for improvement quite quickly, and we're going to see a shakeout of the second tier companies in a year or two. But that's the way this happens, it's a natural part of evolution.
Some of the best writeups I've seen of the iPad in the last few days realize that it's really a new category of device, one which could even replace a computer for a certain class of users. But it's not going to replace a phone or an MP3 player. It's going to cause the makers of netbooks and eReaders to think creatively, though.