Left 4 Dead 2 DLC found?

In some of the Left 4 Dead 2 campaigns you might have noticed a poster hanging, specifically at the end of the Rollercoaster Dark Carnival campaign part, with some rockstars on there called the Midnight Riders.  Now we might call it a rumour or it might be a brand new campaign or new characters that is coming to Left 4 Dead 2 in the future but if you look at the website http://www.midnight-riders.com/ you might be wondering the same thing as me……..