Why not just get a Macbook?
Its small and light enough already?
A tablet that was just like a big old iPhone, with an Intel CPU and running standard OS X would be ace.
Really, how useful would it be?
Not much use for serious text entry without a hardware keyboard is a big problem. So it's just a web browsing slate, which is great but limited, especially if they want £300 for it. If it could connect to the bluetooth keyboard though, it'd be more tempting...
It's only a 13.3" screen yet it's comparable in weight to the 14.1" machines from HP, Dell and Lenovo. I.
If they could tie it in as a main-machine add-on (functionality a la Wacom tablet for use with Adobe Photoshop) or as a portable media browser then it could be good.
I really want Steve to say they'll never bring out the 12" MBP.. so many people moan about it on every Apple launch event it makes me want to punch myself in the face.
It is thinner and lighter than any 14" Dell laptops I have had the pleasure of dealing with. Sure some of the other manufacturers 13" are lighter a thicker but as far as portability goes I see nothing wrong with the MacBook.
I don't think twice about throwing mine in my rucksack and then cycling, so it cannot weight that much - at least not enough to bother me!
The OP wants a small laptop and a Mac so the MacBook is a perfect way into the world of Apple and OS X and all that follows. You know? The buying of black turtle neck jumpers, the odd BOOM! slipped into conversation...