It's no more visually-impaired friendly than the traditional text/numbers CAPTCHA codes (those "type in the string above" verification used in comment forms for many blogs), but the KittenAuth test is not probably harder to hack (since humans can tell the difference between a baby bunny and a kitten, but computer can't -- yet), it's just so damned cute.
KittenAuth is a new system for human-checking that forgoes all the useless random string crap that people cannot read, and replaces the whole lot with pictures of cute animals.The current 9*9 design displays 9 pictures and requires that the user clicks 3 pictures of kittens. The location of the kittens in the grid is random and to make things more fun the contents of the pictures changes too.
Like I said, cute!