I think multitouch tablets in general have access to potentially HUGE market given enough time. Given that a huge proportion of the population only comes online to post on forums, browse news, access facebook etc, using a touchscreen device has to be much, much easier than sitting at a desk using a computer.
Unfortunately, at Apples pricepoint I can't see a huge uptake from non-techies. The iphone is massively popular because although it is an expensive device, 95% of those buying them spread the cost over 18 months including their data/text/call contracts so it doesn't FEEL particularly expensive.
To shell out more than the cost of a low/mid-range laptop on a device which does less than a laptop will (I think) be more than many will want to bear.
I would love an ipad, but when they were announced I set myself a limit of £350 for the most basic version and I won't be crossing that line. Optimistic price perhaps, but beyond that the cost starts to get a bit silly.
I'll wait til they start appearing used on ebay and then re-think things