So Apple announced 'The world's thinnest laptop' a couple of months ago now. After a few minutes on Google however it looks like it isn't.
The Sony Vaio X505 released back in 2004 comes pretty close at 20.8mm which a lot of people used in comparisons with the Macbook Air, which comes in at 19.4mm.
However both of those are beaten out by the ten year old Pedion, built by Mitsiubishi and Hewlett-Packard which is only 18.4mm thick. Sharp however beat out the Pedion with their Actius PC-MM10, which is only 13.7mm thick. It wouldn't surprise me if there are a dozen other laptops out there that are thinner either.
What makes Apple think they can get away with such blatant false advertising?
But then of course Apple should put their efforts into creating a machine which weighs less and has better battery life, you know, work on the two most important features that a mobile computer needs to have, instead of wasting time trying to save a mm at the expense of functionality and then spinning off plenty of false advertising about it.