That cabled bind-off is easy as pie:
All it is is a fat i-cord bindoff, with a cable twist and a purled edge stitch to provide the necessary recess for the cable to pop. It has a little bit of a tendency to curl forward, but only enough for the twist of the cable to show properly. Because of this, it won't add much length, but it does fall nicely in line with the body of the work.
To my eye, a six stitch round cable looks more or less equivalent to a four stitch flat cable. Be aware, too, that the difference between row gauge and stitch gauge will create a softly gathered effect along the cable, unless you compensate with a larger needle for the bindoff, or by attaching only three out of four rows (or whatever works). Or just block it out. Or plan to use it in a way that takes advantage of the slight ruching.
If, like me, you're going to pick up stitches and keep working vertically, just pick up the never-quite-perfectly-tight strands where the yarn was brought around to close the i-cord. Knit from those, twisting each strand as you work to tighten them up and force the cable to straddle the two sections of knitting evenly. For some reason, it's enormously satisfying to me that the neat, tidy back of the work hardly hints at all at what's going on in front:
I can think of lots and lots and lots of ways to use this - as an edging along lapels and hems (use a provisional cast-on and work this bind-off later), lying in heavy bracelets around a cuff, combined with short rows to spiral up a sleeve, as an edge for a structured, felted baguette...endless! (In all this, I guess I'll be pretty embarassed if this is already in, like, Knitting on the Edge or something. For the record, though the idea's probably not new, I did think through this version myself).
Unraveling will be up over the weekend. I have some really interesting questions, and am totally absorbed in writing my answer - a treatise on How To Personalize Knitting, with notes on choosing a pattern, making sure it will fit, adjusting for gauge, choosing a yarn, all kinds of interesting things. It's taking longer than I expected, though (I want to do the subject matter justice), and besides, there is a ballgame beckoning me. See you tomorrow!