These are the promo pics from the show. They are tiny, but you get a feel for them. Shannen and Mark are on the third page. Based on the costumes, they may be doing a cha cha first-I hope so.
http://www.abcmedianet.com/web/showpage/showpage.aspx?global_id=001831&type=asset&typecode=ph
Mark is young but has been dancing most of his life. His parents are considered the King and Queen of the Ballroom and he has won a gold medal in the junior Olympics. He is also the only male pro to have won the show twice. He has a lot of teaching experience and I think Shannen will love him. Based on his tweets they are having a good time together.