According to developer Undead Labs, the Lifeline DLC for State of Decay will be available May 30th, should all go well. It will cost you $6.99.
That's their words, not mine:
That’s right. May 30. $6.99. If all goes well this week, you’ll be playing Lifeline (and the accompanying free Title Update, featuring Rucks in Trucks by this weekend. If all goes well, this may be the first time in gaming history that a game was released BEFORE the official public target. It’s a long story, best told over copious quantities of frosty beverages, but the short version is that both the Undead Labs team and the crew at Microsoft has been burning the midnight oil to make this happen before State of Decay celebrates its first birthday.
The content has entired final certification, which essentially means that it's gone gold and is being verified and combed over before digital release.
