Note that radical Islamic clerics who support violent reaction to the situation in the middle east are now being threatened with the rather medieval crime of "treason". I believe the punishment is supposed to be deportation to the tower followed by decapitation. Now I think terrorism's wrong (including that perpetrated by Bush and Blair around the world) but I think people are entitled to their opinions. Without free discussion on the subject these problems will never be resolved. Just because someone's ideas are offensive, we can't make it illegal for them to hold and express those opinions. Like the BNP, their views are disgusting but we have to let them have them and express them. It's a basic human right.
Of course encouraging people to be violent is and should be a crime. But stating that you believe, for example, that a violent response to the occupation of Iraq is justified, that's your opinion and you are well within your rights to hold it and state it.