Rumours have been spreading around of an October 11th, 2005 release date for Quake IV.
Other retailers such as Amazon.com have been claiming the same exact release date for Quake IV - October 11th, 2005, also updating the box image coverart. Same goes for several other retailers.
Although neither Raven Software, Activision, or id Software haven't confirmed this yet - this news should be taken with a pinch of salt, nothing more.