Now this may be a cool tie in for fans of the Capcom game when they see it but if you spin around in the same room, you'll see something even cooler. On the opposite wall there's a posting about the possibility of an M60.
In the new Left 4 Dead 2 levels, the M60 was added to the survivors' arsenal with great results. What does this have to do with a posting on a wall? Well the posting on the wall is by none other than Crazy Dave of Plants vs. Zombies fame.