Under the Features tab, the description only states different poses and positions as the included items.
Do the spirit poses automatically set up the character as a transparent ghost, or was this post work in the promo pictures?
Making the figure ghostly would require the modification of material settings (or compositing two or more renders in an image editor), it isn't in the pose set.
You could also use pwGhost shader or one of the free ghost shaders from ShareCG.
There's a set by Portrait Studio, I think it's in the Rendo freebies, that works in Poser. Not sure if there's a Studio version, though, it was quite awhile since I got those. But it was made specifically to use with the Haunted poses.
Thanks for all the answers since I really wanted the ghost effects more than the poses.