A web search engine that ranks pages by readability seems like an outstanding tool for teachers and students alike. Indeed, some day Twurdy will be a great research tool, but for now the beta is a bit awkward. It is still a great resource for teachers to use as they refine and differentiate their resources. For example, you can find several articles on the same topic at different reading levels. Useful, but not a replacement for Google by any means.
I recommend using the "Twurdy with Pop" button for the best results.