The information posted by TGUY82 is not entirely accurate.
The adductors are a small supporting muscle group in your leg, and should never be the focus of intense, specific exercise. They are not the primary mover in a squat at all, unless you're doing it wrong.
Yes, squats work your glutes (butt) and will be responsible for the visual change there. Good job! :)
The primary movers on a squat are your quads and your glutes.
Spark's info on squats and what they work: www.sparkpeople.com/resource/exercises.asp
Livestrong - What muscles do squats work out? www.livestrong.com/article/416344-what-mus
Livestrong - what the adductors are and how to work them: www.livestrong.com/article/417368-adductor
Additionally, I'm not quite sure what was meant by "make sure your knees track out over your toes", but your knees should never pass over your toes in a properly performed squat. You should watch to ensure your knees remain no further forward than just over your toes - they should not poke out in front of your toes.
Edited by: UNIDENT at: 1/12/2013 (21:40)