KISSmetrics has a post explaining how the tracking works. http://www.kissmetrics.com/how-it-works They claim that simply using AdBlock is enough to defeat the tracking. They also claim "KISSmetrics has never, and will never, share anonymous customer activity of what people did on customer A’s site with customer B."
"These services are using practically every known method to circumvent user attempts to protect their privacy (Cookies, Flash Cookies, HTML5, CSS, Cache Cookies/Etags…)"
They may not share information about specific users, but doesn't mean they don't use it to sell information in some aggregate form.