The demonstrations in Athens are against the austerity measures imposed by the government but also celebrate the uprising that in 1973 helped overthrow the ruling military junta. Some firebombs were thrown at police as the protesters marched to the U.S. embassy. Although there have been reportedly no arrests or casualties as yet, the presence of a large number of protesters together with a huge police presence could lead to violence and arrests.
The police used tear gas and stun grenades to stop the progress of the march temporarily. The U.S. had supported the former military government and saw it as a defense against communism.
The new government of Prime Minister Papademos just recently won a confidence vote in parliament by an overwhelming 255 votes to 38. However Greeks are still taking to the streets to protest the austerity measures.
Papademos is a former banker and unelected. Papademos must ratify the bailout terms agreed to by the EU in October. In return Greece will receive 177 billion to keep it from going bankrupt. Signs are that Papademos may be able to push the package through parliament. The main opposition will be outside the government and in the streets. For more see this article together with a video.