That looks like what I have heard called a "honeycomb" stitch. You can find a pattern for it in Mason Dixon Knitting in the pattern for the "Big Dotty Cushion." It's essentially two rows knit in color A (in your pic that would be the black), then you switch colors and slip two stiches every six stitches (*k6, sl2*--this isn't exactly right, but you get the idea). You could probably look this up under slip stich patterns as well.
The only thing about this pattern is that it will only look good on one side. And it reeeeeally needs to be blocked. I did something in this stitch in cotton and I was not very happy with the results. I recommend wool, or something that stretches and blocks well.
Thanks - this points me in the right direction. If I ever knit this scarf, I'll be sure to post it here.