Well, everything goes in cycles... makes sense we'd eventually exhaust all the possible fad diet permutations and go back to one of the original fad diets! I'd imagine it's probably been altered slightly from the original Atkins diet, if only so it can have the caveat that all the flaws with the original diet have been ironed out.
It's an odd trend, but one that repeats time and again. Someone famous or a well-known media outlet recommends something as healthy or weight-reducing (bonus points if you're able to do whatever you want some of the time), and enough people take it at face value to give it momentum. More people try to cash in, and you have your new fad diet/exercise plan. This tends to ramp up in January (for the New Year's Resolutions people), and in the spring (for those who want to be able to wear only a bikini/pair of swimming trunks at the beach in the summer without feeling self-conscious), and they never work out, unless, as other users have pointed out, you change your entire lifestyle to support your new weight. Although, quite depressingly, most fad diets tend to get popular on the back of 'hey, for X days a week you can eat what you like!' Which is really the opposite of the attitude you want to be cultivating here.