I learned the technique from the Philosopher's Wool book, but I found that it doesn't actually twist the yarns. If you're knitting with white and carrying black across the back, there will always be some show-through, but in this case the yarn just kind of sits behind the other stitch, so I find that it doesn't show through much. I don't think it makes it tighter, either, but I've gotten into the habit of stretching out the stitches on the right-hand needle, anyway. I just don't want huge loops.
I haven't gotten a picture yet--I actually forgot about it, I will get to it later.