Don't get your hopes up for the 'Miracle' and 'Apocalyptic' DLC packs for Left 4 Dead 2, they were only included to make Microsoft happy.
When gamers took a peak at the inner workings of the Left 4 Dead 2 demo they found something very interesting, namely code for kicking people from an Xbox Live session if they didn't have the right DLC packs, leading us all to believe that Valve had some DLC planned, and perhaps even ready to go.
Unfortunately, Valve's Chet Faliszek has rather spoiled that idea by revealing that the names are just placeholders put in for Microsoft testing.
"If you're reading in the forums and you're reading about the "Miracle" DLC or whatever, that's test code," said Faliszek. "To get tested through Microsoft certification, we had to do test scenarios with DLC. We haven't actually come out internally with what we're going to do yet."