This is completely untrue. I'm afraid that most of the people that's rioting now against this proposed law has read Grillo's blog but certainly not the law.
The ROC (registry of organization operating in communication) is free, so it is not a tax; and the registration is mandatory only for companies, not for people that run blog or personal sites.
The new law design could have been written better, but it is a semplification of the current Italian law that requests a costly registration for every printed or online journal.
Free speech on the web is not endangered by this law.
S*