This Rowlf was released earlier than 2011. From what I can recall, he first started showing up online in early 2009. He was released by a South American Department store chain called Falabella -- they're in Chile, Argentina, Peru and Columbia -- as a part of a promotion that also included plushes of Kermit, Fozzie, Miss Piggy, Gonzo and Animal (i.e. the "usuals"). I am unclear on how the promotion worked, as I don't speak a lick of Spanish, but I assume it was a purchase-with-purchase kind of thing. Each of the characters was released in a number of different sizes, and I've been hunting them down over the past 3 years.
I actually have three Miss Piggys (18-inch, 9-inch, and a hand puppet), two Gonzos (24-inch & 18-inch), three Fozzies (24-inch, 16-inch and 9-inch), two Animals (24-inch and 13-inch), and two Rowlfs (15-inch and 8-inch) in my personal collection. And yes, a 24-inch Rowlf was on eBay a few weeks back; at the time, I did not realize that I was missing that one, or I would have bid! The only character that I am missing entirely is Kermit who was, frankly, kind of scary looking.
So no, Rowlf is not entirely new... but he IS pretty hard to track down. Hope that helps!