This is a great topic for high schoolers because they all seem to have an opinion on censorship (and so do their parents!). Many of them feel that censorship should not apply to them, such as explicit lyrics warnings on music, rated R movies, etc. I then ask them why they could go to the library and check out the book version of a rated R movie, though.
We discuss methods and purposes of censorship, then boil the responses down to three basic types: political, religious, and moral (there are more, such as corporate, military, etc., but we don't really get much into those).
Another approach may be to list some popular books that have been banned that they've probably heard of, such as "Alice in Wonderland", the Harry Potter series, etc. (see link for American Library Association's list).
Stage a class debate on censorship: should schools be free to teach whatever they want? Should children be free to listen to any music they want? Should anyone be allowed to watch rated R movies? The questions are endless, it seems.
I highly recommend, if you haven't already done so, Bradbury's Coda at the end of the novel Fahrenheit 451 and read his views on censorship. I also love how one district ironically blacked out all of the "bad" words in the novel with a marker: a book highlighting the devastating consequences of censorship being censored!
I think that if you are teaching this or explaining this concept to a group of older students, there can be much in way of success and discussion on the point of censorship. I would start out by discussing why there is censorship. What is the purpose of it? Then, I would link this to the reasons why censorship and burning of book is embraced in Montag's society. The larger issue here that has to be brought out is that if books contain ideas, and ideas cause change, why is censorship an approach that ruling bodies or governments take? I think that being able to fully explore or discuss this idea in the book would allow a greater understanding of the topic. I would then move to our own setting. Do we have censorship today? Perhaps, talking about a post 9/11 world and whether or not censorship or consolidation of power is a part of this design. Additionally, the question of is censorship present and is that a good thing should be raised, as well in order to bring to light the possible and potential difference between what is and what should be.