I’ve just added my newest poster to the shop for the Naked And Famous show at the Showbox Sodo on 4/24/12. These posters were printed on a really cool semi-translucent plastic paper.
If you hold the poster up (either side!) to light, you get a subtle glow through the lighter ink colors. (I had toyed with the idea of printing on both sides, but the plastic paper ended up being a little too opaque for the two-sided effect I originally had in mind.)
Since there is a bit of transparency, the ink colors are a little lighter in person than in the JPG above. This photo of the uncut poster from the print shop shows how the light gives the poster a glowing effect.
Did you get here from the shop?