Since a long time (at least 9/11) there is a lot of discussion about the way terrorists use/will use the Internet,
It is clear that the Internet is used for publicity and communication. There are experts saying that the Internet itself will not be a target for an attack for terrorists because of this fact - they would destroy one of the most important communication channel.
Will they use the Internet as an attack channel to critical infrastructure? Well, I hope that we will not see that ever happen.
What I never thought of is, that they seem to use the Internet for "fund raising". Read yourself: http://www.zone-h.org/content/view/14508/30/