Linear equations for 2D-2D rigid registration

I realize this isn't exactly a matlab question, but it's related and I'm sure some of you are quite knowledgeable of linear algebra. Could somebody help me understand the math here? http://dominionsw.com/wordpress/?p=111 Specifically, I don't understand how he converted the equation with the rotation matrix to the linear equations. For instance, what's with all the 0's and 1's?? I took a course in linear algebra but it was quite a while ago. A walk through for this step would be much appreciated!

Thanks!