I wasn't talking about netbooks, I said tablets. There are many current shipping tablets out there, contrary to what some Apple fans believe (no, Apple won't be the first to ship a Star Trek like Pad thingie)
Nokia N810 :
Samsung Q1 :
HP Tablet PC (IMO, the best one, best of both worlds, still wouldn't buy it) :
Archos line, first the 9" based on Windows 7, then the 5 based on Android :
There are others, but you get the point. There's already a lot of products out there. Single purpose e-readers, multi-purpose Media consumption tablets, etc.. A lot of the stuff said in this thread is already out there in terms of shipping products.
Of course, this is something Apples excels at. Wait till other players make all the mistakes, fix them, and then ship. However, Apple is good at doing this in booming markets with good consumer mindshare and plenty of growth, like the cellphone and MP3 player markets were when they introduced the iPhone and iPod. The tablet market is neither booming, nor really growing, nor does it really have good consumer mindshare. Hence why I think this will be a niche product.