Ok, like most men I have difficulty working out what 10" looks like. In order to clear things up I started looking for real examples to help people visualize it.
Apple's possible 10" touch device will most likely (based on iphone ratio) be a 9" screen with a boarder. This then would be slightly larger than a DVD case.
Also if you scale up the ipod touch (10" = 4 ipod touch) then it would weigh 600g (4 x 125g).
So it may well be smaller and lighter than you think.
I know the device will be very popular as my wife has always said she would love a 10".
A better comparison of size is to that of your mouse pad... the average mouse pad is about the size of this device + frame