Ahhh, those carpet squares -- designers love 'em! A few years ago I knew if I was in the home of an interior designer because of commercial carpet tiles creatively placed throughout (we are very resourceful with our extra samples)!
Now these modular squares are sold for residential use online, http://www.flor.com/ in catalogs, and I saw them on an end-cap at Target last year.
(Here's a photo from my friend's cute baby room).
For me -- I'm content with my mini carpet coasters!