ZDNet is reporting that the US Senate has failed to vote on extending a moratorium that prevents state and municipal governments from charging taxes on online taxes. This moratorium has been in place for the last three years, and is the reason why you can order those books and DVDs online without paying any tax. It will expire this Sunday due to the inability of the US Senate to pass an extension of the law, clearing the way for every local government in the US to try and grab its "fair share" of the pie.
You can find more information in the short article at ZDNet. Thanks to forum member VSeward for alerting us to this development.