Their explanation of the universal cookie ID issue is rather silly. If you're a client of Kissmetrics, your visitors have a cookie scoped to your domain with the visitor's universal Kissmetrics ID. All of the database segregation in the world won't prevent any two or more Kissmetrics clients from collating visitor data on that universal ID, sent in every header on every pageview. Whether any clients are actually doing that, I have no clue. But claiming that permuting that universal ID into client-specific ones rendered when the clients view data actually protects visitors from said collation is just wrong.

See Wired's screenshot here: http://www.wired.com/images_blogs/epicenter/2011/07/Screen-S...