I wish they showed how many people weren't using Private Browsing. For all we know the spikes might just be because more people are browsing the internet at those times (I suspect that's the lunch spike).<p>In the context of this discussion, percentage of Private Browsing activations would be more useful.
Apart from understanding how much time people spend in private browsing, here's a recent paper that talks about the technical details of private browsing mode of popular browsers (Firefox, IE, Chrome and Safari).<p><a href="http://www.usenix.org/events/sec10/tech/full_papers/Aggarwal.pdf" rel="nofollow">http://www.usenix.org/events/sec10/tech/full_papers/Aggarwal...</a>
Amazing that people are able to find what they want to see but don't want others to know that they wanted to see and be done seeing whatever they saw in as little on average as 10 minutes of time.
It looks like it could be providing a false sense of security for people at work, despite the warning that Firefox gives the user about the employer and ISP still being able to track what he's doing. Are people really reading that warning and understanding what it means?