Yes, it's true—or at least, the folks at Eurogamer have dug up pretty convincing evidence that Assassin's Creed III won't hit PCs and consoles simultaneously. A "promotional image" snagged by Eurogamer.cz says the title will be out on October 31 for consoles, but PC gamers will have to wait until November 23 to get their hands on it. Ubisoft has refused to confirm or deny the delay officially. It told merely Eurogamer, "The Windows PC release date is still to be announced."
Considering Assassin's Creed III trailers have promised a launch on October 31 in Europe and on October 30 in North America, Ubisoft's statement might as well be a confirmation of the PC delay.
If the November 23 date is correct, then it likely applies to the European PC release. North American games usually come out on Tuesdays; in this case, that might mean either November 20 or November 27 for Assassin's Creed III. We'll see what Ubisoft says when it's ready to announce the PC release date.