EU Cookie Law Complience Message is a WordPress plugin by azuliadesigns that creats a small banner at the top of the guest’s browser that greets them with a message that can be customised from within the plug-in settings page.
This method relies on implied consent and you should ensure that this method is correct for your website. If you are relying on implied consent you need to be satisfied that your users understand that their actions will result in cookies being set. Without this understanding you do not have their informed consent. – http://www.ico.gov.uk/news/blog/2012/updated-ico-advice-guidance-e-privacy-directive-eu-cookie-law.aspx
Download plugin: http://wordpress.org/extend/plugins/eu-cookie-law-consent/