Banned Books
In the US, books can be banned at a very local level, in school districts and libraries, or at the state level. I think instances of nationwide banning are very rare, probably none recently. The website below lists loads and load of banned books and who banned them and why.
It's interesting that sometimes books are banned for one or two words, sometimes they are banned because people object to the world they portray, no matter how true it is to real life.
I think in the UK (maybe other European countries too) banning is a national phenomenon, like the recent banning of the latest Kitty Kelley book, the one about the Bush Dynasty.
In the UK it seems more serious, in that it is an overall gov't policy that makes the book illegal throughout the nation, whereas in the US, it's just a formal censorship against having it in the school curriculum. No books are banned from being sold in stores or being sold. In the case of the Bush/Kelley book, the excuse was that the libel laws in the UK are so stringent that the book would certainly come under attack and lose. Funny, Kelley writes these books all the time (incediary unauthorized biographies) and has never lost a libel case--apparently she's very good at sourcing her material. So, what's that about?
That said, there's an embargo being disputed right now on books authored by Iranian nationals. Not sure of the details offhand, but it is a political embargo meant to restrict trade, though it seems to only restrict information exchange and hurt US publishers.
http://www.banned-books.com/bblist.html