it would be nice to have a simple way of customizing text and format of the privacy optout messages. as it is you can only customize the iframe, but font, size an content of the messages are unchangable.
if you want to customize the opt-out messages you will have to edit the appropriate language file and if so the optout.tpl - wich might be a bit tricky for a rookie…
I know this topic is 9 month old, but i think it would be good to have an easy how-to somwhere, or a CSS file. This feature is one of the key features that made me opt for piwik, since i’m very concerned about transparency on my website. I think also visitors that see that message might start questioning how they are being tracked on internet, which is a healthy question to ask yourself, because when your a plain user, it’s not like anyone is going to tell you this kind of stuff.
However, since i know german i’ll have a look at that howto! And i love your system (just had to say it!)