IIRC, the UK's existing pornography laws make a distinction between, for example, partial nakedness (page 3 of the sun - not regulated) and sexual nakedness (what you think it is - regulated, restrictions on who can buy, what a licensed shop is, etc). There is also a separate rating above 12, 15, 18, which classifies films as subject to pornography controls or not. Internet sites are completely unregulated compared to video tapes/DVDs, under these laws, which is why they're updating them.

I suspect that films (girl with the dragon tattoo springs to mind) would not be subject to it because they aren't presenting the rape as sexual; it is seen as a crime in the film, which isn't primarily a film about rape/sex (obviously I can't speak for all films.)

The grey area and line drawing are a problem with laws like this, though, as several people have pointed out - I am sure there are films (horrible ones that I haven't seen) that come close to glorifying rape, or depicting it as desirable/sexual - whether those would be part of the law would be up to either parliament to specify, or up to the courts to decide later in case law.