I know it's a little out of date but it is something to keep for reference.
http://www.theregister.co.uk/2008/03...rul/page4.html
The quote below would suggest that the Profiling is "Always ON", for
the simple reason that the Webwise System can tell you; by "Page
Injection", that they are profiling but not allowed to serve OIX ads!
-----------
KE:
The conversation over opt-in/opt-out is blurred by the one about
transparency. They want to always be aware about whether something is on
or off.
So we're going to do something unprecedented, and you'll never see this
anywhere. Which is, as they continue to browse periodically you're going
to see in an ad space "Webwise is on" or "Webwise is off", so it's more
like a feature. Frankly, it's bad business to have people feel like
something is being forced on them. Google stores everything you search,
but it never says, "look, by the way we're storing all this and we keep
it for a year".