I started incorporating the sumo stretch spatts demonstrated and it has really helped quite a bit. I definitely reccomend it. My first set of squats always felt a little awkward as my hips were still a little tight. It always took one set under my belt to get really loosened up but the sumo stretch before the first set has made a huge difference.
One very important bit of advice though. Make sure your feet are perfectly in line with your thighs when performing this. Turn your feet out or in too much and your knees will quickly start screaming at you.