According to Anita Grossman Solomon this is an old Italian design but doesn't give it a name, although it is very much like a single point arrowhead block. Here is a photo of a quilt that she has done using it.
http://2.bp.blogspot.com/_MmhuWVML-r...impler+OIB.jpg

Anita is registered here on the forum and this is her blogspot
http://makeitsimpler.blogspot.com/