I can remove a page from a single list of results, from all future searches I do, or remove everything on the domain entirely. Once a site has been removed from search results, an easy-to-overlook blurb at the bottom of the page informs that “Results have been omitted”, and offers a link to restore them.
I did a bit of searching on the topic, and discovered that “a small percentage” of users currently have the option.
I’m still trying to decide if this is a good idea or not. I have nightmare visions of the system being beaten (as greasemonkey gets around Google Print viewing restrictions), and companies removing their competitors from Average Joe’s search results.
That’s probably over-reacting. But something deep down inside of me cringes at the idea of users having censored searches, self-controlled or not. On the other hand, spam-site blocking does seem like a useful application.