The lights are on
The Deus Ex ARG at their official site has ended, revealing the game's first DLC. The Missing Link will be released in October, and will cover Adam's three-day disappearance in Human Revolution.
Players will control Adam after his augmentations become disabled, and are tasked with escaping a freighter. The site says you can "rebuild Adam's augmentation from scratch," so a respec option is likely. No specific date has been set for The Missing Link.
Source: Deus Ex Official Site