This post is not really about the iPad it's about memes and production costs.
The concept of the slate computer has entered popular consciousness, in no small part due to Apple's razzamatazz. And undoubtedly it will be a success. The interesting thing is that already there are two possible alternatives - the JooJoo (née Crunchpad and possibly in a death spiral) and a hacked up no name Chinese equivalent with poor battery life.
Of the two, the Chinese machine is the more interesting - it's a simple low cost hardware hack - and something similar combined with ChromeOs or Splashtop would give a similar web viewing content consumption experience. And as Google keep on telling us these days the browser is the user interface - something which is a danger for Apple, as it becomes difficult to claim to be unique and special when other people can offer an equivalent experience. And for a web based experience its browser stability, browser performance, and underlying operating system stability - something the firefox/linux combo certainly delivers.
Apple's user interface experience, and team of dedicated, perfectionist designers, probably means that the iPad is very good at what it does. But with Apple rumoured to be making around $200 profit on the hardware in each iPad, and given that production costs for each equivalent device must be roughly the same there's obviously room for someone to undercut Apple with something pretty similar - after all the Newton lost out to the Palm Pilot, which while cheaper, was by no means an inferior device.