Digg Bar - Something Dangerous?

I found a reference to the Diggbar at TechCrunch (and other locations). It is an intriguing idea: You go to the site you like to see, and then you add "digg.com/" in front of the URL in the address bar. For example, you start with "http://whitehouse.gov", but then you add "digg.com/" so that it looks like "digg.com/http://whitehouse.gov". Press enter and done. What happens is that digg.com knows about the page that you currently see, and it serves possibly some ads on the top of the page, along with useful stuff: a short URL in the address bar, an opportunity to rate or recommend the page, find related content, or with one click create a Twitter entry or an email. All very easy, no need for installation of any browser plug-in or other stuff. But... it somehow feels odd that all content you access can be monitored by Digg. True, Google reads my email. Yahoo knows my RSS feeds. But browsing through Digg? Let's learn more about this.