Here is our first new Build a Seam (BAS) Challenge stitch for 2012! I have found it called the Portuguese Stem Stitch as well as the Portuguese Knotted Stem Stitch. It is a less common stitch but certainly an interesting one to look at! It is not difficult and I'm including step by step photo tutorial below.
In case the photos are not clear enough, I found a good set of stitch diagrams at the Stitch School here.