Tablet computers have been out for years and years. I do not want a "tablet computer". The laptop is a great form factor for general computing.
But that's just me. When people were wondering what kind of netbook Apple would come out with -- I said then (more than a year ago) -- that I didn't want a netbook, I wanted a large iPod Touch.
I don't think the processor in iPad is fast enough for full functionality of OSX. One could make it work, but will be really slow.
Apple wanted something between an iPod and a computer. That's what the iPad will remain. However they still got the legal rights to the name iSlate.
I would prefer Airpad...:p
I'm pretty sure, that the success of the iPad will have a major impact on a decision, if a "MacBook Touch" would make sense for Apple or not.
Personally, I believe, that we will see an Apple product in 15" within the next three years. MacOS 11 might be fully touch enabled......