Watched their new PBS special last night. They use pipers in several places. This youtube link shows a group of them in a tartan I don't recognize at about 1:20 mark, and one in what appears to be Dress Stewart at 5:00.
http://www.youtube.com/watch?v=S1tDVSAqOpw

There is also I believe a piper in a saffron kilt at one point - makes sense, the ladies ARE Irish, I believe.

Fantastic show. They can surely sing, and their backup musicians are very good as well. There is a drummer I particularly like. And of course being a great fan of bare shoulders on lovely ladies...