L4D2: "Miracle Pack" and "Apocalyptic Pack" are spaceholder names only
During his Left 4 Dead 2 talk today at EG Expo 2009, Valve's Chet Faliszek explained that the DLC pack names found in the demo were spaceholders only, put there as required test by Microsoft.
"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."
Also, as far as the original survivors are concerned:
"They're not dead, so we'll see what happens with that," he said. "They're not undead either."
There's loads more through the links there.