I'm totally against this. Evercookie might seem nice, but it actually intrudes peoples privacy by writing to other things than only the cookie space. The user should be able to opt-out from Piwik. This would also be against a lot of laws in most countries (e.g. in Germany)

mhmm ok, than it should be an plugin.

I'm not sure, if this is against german law, as we just create an anonymous tracking code.

It's sure against the law, if the information is connected to a real ip or a user account - without the ok of the user.

I'm sure, other statistik software uses similar technics to identify the user.

Interesting but I'm marking as wontfix for now. We can revisit after we've revamped our cookie implementation (eg scaleability and first party cookies) and support for tracker (javascript) plugins.