A swag of ways to block the DiggBar have been posted up at Daring Fireball over the last couple of days, and there are “fixes” for most of the widely used blog CMSs. There’s also some PHP you can add directly to your files should you feel so inclined.
But unlike normal URL shortening services, when you load these Digg URLs, rather than redirect you to the original URL, Digg loads a page which frames the content of the original site. As a user, what you see is that the URL in your browser’s location field remains digg.com/1234, and the content of the destination site loads underneath a Digg-branded toolbar. This, of course, is total bullshit.