l am extremely curious to see what "A Spaceman Came Travelling" sounds like. I've always liked that song (if it's what I think it is); it'd be interesting to hear their take on it.
I also hope it'll become available to us someday--maybe iTunes like maloney said?
Just type "A Spaceman Came Traveling Celtic Woman" in the search box on Youtube, there are many videos of it there. Lisa Lambe sings it.