You may be right! I didn't notice this:Hmmm I figured it would since the last pic on Rightstuf shows the same stock photo with the "Steam code" image.
Along with the game this edition includes a tall-standing high quality acrylic figure of Super Sonico with new original artwork by Tsuji Santa plus collectible cards with art from the game. You will also get a Steam Key so you can add the game to your Steam library.
So it sounds like it should be included. I know for Steins;Gate, it wasn't [had to order directly through JList], but it could be a different situation here.