Gamesindustry.biz has posted a statement from id Software and Activision about some Quake IV concept art that's been leaked, "allegedly after being taken from a company network by hackers, according to some sources." The report goes on to say that it's possible that at least one website received some form of legal warning after posting the images, and offers this from the official statement:

"We do not know the source of these leaked assets. Please be warned that id Software has instructed Activision that we are not to work with any magazine which uses any of these assets. If any magazine does so, id Software will not allow any assets for id games to be sent to these magazines in the future."