This is an interesting phenomenon on the Internet: There is one source publishing the statement that they picked up an Internet announcement by Al Qaeda that they will start a cyber attack on November 11th: DEBKAfile Exclusive: Al Qaeda declares Cyber Jihad on the West. From there on the blogsphere went ballistic (the article was published October 30th). If you search for it, you will find quite a lot of articles and blog posts referring to the DEBKAfile site. Nobody actually really questions the source. I am definitely not in a position the quality and depth of this information as I do not have enough experience with DEBKAfile at all. It is just interesting to see how information spreads without really thinking twice about the trustworthiness of the source.
As you know, I wrote already several times about Cyberterrorism and there is definitely a certain probability that something like that might happen and that it might even happen on November 11th. However, I think that a certain level of skepticism is always good to have unless the information is proven by a second on third source.