Agreed Bees, I think all this really does is create work for some poor hosting company, or if the site is hosted by MPAA staff themselves, some poorsysadmin.
The generals at the top would be unaffected besides from having to read a few extra emails and maybe an extra topic on the agenda of the next meeting.
I guess the question is, if ALL of those people who took part in the attack wrote to their local member or most closely affiliated loby group, expressing their outrage, how much would it achieve.