splityarn calls this the "Easiest Knitted Sweater Zipper Install Ever" and it looks like it might be. I haven't tried it yet but I'll let you know if I do - my one attempt to put a zipper into a knitted sweater came out OK, but not this nice.
You’ve cast on the right amount of stitches, and you’re ready to start your project. Now the next big step…join in the round! This fun technique is easy to learn and will allow you to work all those circular knitting patterns you’ve always wanted to try.
Knitting Tutorial: Joining Stitches In the Round with a neat, easy and invisible technique. Just make sure that your stitches are not twisted on the needles before joining. GOID Idea for joining in the round Should be a better join solution.
The Russian Cast Off (Russian Bind Off) is a looser, stretchier, and more elegant way of casting off than the traditional method. It works particularly well as a finishing to ribbing, especially on a ribbed collar or a ribbed band (for example on a hat).