I just watched the Swedish news (01.06.2006 Rapport on SVT1). The Pirate Bay story was headlining, and what they said was this:
(Paraphrasing, and forgive sloppy translations of departments and whatnot. Assume more or less Swedish equivalents.)
The US organisations (*AA) had gone to the White House, to ask the White House to get something done about those evil Pirate Bay guys. The White House talked to the Swedish government.
A delegation from Swedish Justice Department, Attorney General and police (or various types of the sort) went to the US and talked to the Americans. When they came back, they concluded that they had shaky legal grounds upon which to take action (this had been looked into closely by the Swedish Attorney General's office earlier), and they told the government so.
Upon which they were ordered by the relevant Swedish minister of [something or other] to take action anyway. So they did.