Bruce Schneier posts on a story being reported in the Seattle Intelligencer. Greek and U.S. officials in Greece apparently had their phones tapped for over a year before the 2004 Olympics
. From the article: "It was not known who was responsible for the taps, which numbered about 100 and included Greek Prime Minister Costas Caramanlis and his wife, and the ministers of foreign affairs, defense, public order and justice. Most of Greece's top military and police officers were also targeted, as were foreign ministry officials and a U.S. embassy number. Also tapped were some journalists and human rights activists."
Schneier gives a bit of technical background
on how the tapping was accomplished.