Deus Ex: Human Revolution websites, erecting an "Owned by Chippy1337" banner and signing some names and aliases below (a possible red herring). In IRC chat logs, obtained by former Washington Post reporter Brian Krebs, the hackers also claim to have stolen the personal data of "at least" 80,000 users. So, first things first: If you've registered on an Eidos site or with the Deus Ex site, now's the time to change your password (we should all be used to this by now).
Eurogamer has spoken with "Venuism," one of the hackers implicated in the theft, who clarified that the "src" (source code) the hackers allegedly obtained pertains to the Deus Ex website and not the actual game. As of this writing, the Deus Ex website still isn't back to normal, while Eidos.com, which was also apparently compromised, appears fine now. (Venuism maintains that he and the others listed below the banner have been set up by a rival group.)
Most troubling, Venuism suggested that the stolen user data -- the extent of which is unclear -- had already been leaked. We've contacted Eidos parent company Square Enix for an official comment on the situation.
Update: Square Enix has confirmed that Eidosmontreal.com and two of its product sites were compromised. The company states that 350 job applicant resumes "may have been accessed" and those individuals are being contacted. Furthermore, 25,000 email addresses, which were "not linked to any additional personal information" were obtained. Read the full Square Enix statement after the break.