Buffalo Attorney Jeremy Colby points out that courts may take judicial notice of information publicly announced on a website if the website’s authenticity is not in dispute and capable of ready and accurate determination. Jeremy presumes the same ruling may apply to blogs.
Though this is going to vary dramatically by blog, over time you are going to see courts accept blogs as they do law reviews. And I can just see a lawyer saying “Judge, you can take judicial notice of the blog, it’s one of the top 100 at Technorati.”
As way of background, judicial notice is a rule in the law of evidence that allows a fact to be introduced into evidence, without the need for a witness, if the truth of that fact is so notorious or well known that it cannot be refuted.