When I was at the Minnesota Center for Book Arts for a class recently, these were floating around - of course I had to grab one! Initially I thought it was a photocopy (although the paper was awfully nice to be a photocopy), but when I was applying some Mijello Blue watercolor to it last night, I realized it was definitely letterpress printed. (No impression from the type on the back, but it was definitely printed with rubberized ink.)
I applied the watercolor with a mop brush and when the paper was wet, I started using a crumpled paper towel to both blot up excess water and leave some nice marks.
Of course I saved the paper towel. Of course it will be coming to an art journal page near you soonishly! :)