I have a feeling that there won't be a clear answer as to whether or not that is in.
They key to the definition of a disc being in the basket is it has to break the plane of a line from the edge of the basket. I am not sure exactly where this line exists. If its the outer edge of the basket, yes it is in. If it is the inner, no it is not. If it is the middle, then maybe, I can't really tell from the photo.
also, sorry for the shoddy wording, but the PDGA site is down a the moment and I can't access a rulebook.
P.S. - My initial reaction to that is that it is out (however, i have never actually seen this happen during a round, but have seen a disc hanging by 2 nubs, which I counted in, because a very small part of that disc clearly broke the plane coming from the inside of the basket)