It would be nice to have some kind of automatically generated disclaimer ("This site uses PIWIK web analytics...") which pays attention to local PIWIK settings (e.g. anonymize IP enabled/disabled). This could be added to the privacy manager plugin in a text area from where it can be copied and pasted into the tracked website.
I think the Disclaimer is a great idea to consider separately from the opt-out iframe, reopening the issue, refs #2889
Proposed Information displayed in the disclaimer:
This text would be generated by an API and available in any format, but also would be embeddable via a widget in any web page or app.
I have an public relations idea. If a site tracks visits through Piwik with the default level of data collection or less, and does not send any data to any third party, it could display a symbol sayin "Piwik Privacy". This would stand for a certain level of privacy protection, since the only data that the site would have about a user is * What Piwik collects, in its default mode, and * Whatever info the user explicitly gave to the site. Thus, even if the site commits the worst possibe betrayal. it can't tell anyone more than that.
It should be mentioned there that we still recommend people to contact a local lawyer to figure out which information is necessary on a website. Maybe in some countries, such as Germany, they have to put some other specific information on it (and translated). Just to make sure people don't think they can copy/paste this text and everything is good.