In a sense the "Cookie law" is a confusing misnomer. Not only "cookies", but also local storage, flash cookies, plugins, toolbars, and even resources like images, HTML, CSS and JS fall under this law.

The Dutch minister spoke of (freely translated): "Everything that reads or stores your data on your appliance, without permission, without a functional goal other than tracking".

Some techniques like browser fingerprinting ( https://panopticlick.eff.org/ , but also possible with http://modernizr.com/ ) don't store anything on your appliance, but would still fall under the "reading your data from your appliance" part of our law, if used for tracking purposes.

You would need permission to use the "grey" technique from the article. Even if you were to store that data in aggregated form.