Well, I had a long explanation all typed out to answer your questions, but the site timed me out and I lost everything so here is the short answer.
Art quilts are typically defined by having at least two pieces of fa
ic pierced through, ie quilted, each layer by, usually, thread and/or yarn. After that, anything goes. This organization has some good examples:
http://www.saqa.com/
I personally use this definition for my work and then add whatever media with help me express my idea/design. In the past, I have used paint, markers, photos, paper, metal, foil, glass beads, etc. One is only limited by one's imagination and, perhaps, finances. lol.
What you see here is my base, just like a blank canvas, to which I will add the other layers of content/design. This base was created by sewing two piece of fa
ic together. The piece on the left, is a type of fa
ic used in traditional, functional quilting. All I have done to it so far is cut and sew it. The other piece is a cyanotype on fa
ic that I created with photographic negatives, transparencies and lace. Go here for more information on cyanotypes
http://en.wikipedia.org/wiki/Cyanotype