From Naharnet:
The United States :
“We were shocked by this assassination, we view it as an act of terrorism,” said Undersecretary of State Nicholas Burns.

Britain
“Clearly we condemn it. We are dismayed. There are enough problems in Lebanon already,” Beckett told a London press conference with her Israeli counterpart Tzipi Livni.

British Prime Minister Tony Blair said:
the killing was “completely without any justification at all.”

French Foreign Minister Philippe Douste-Blazy said the murder was a “new attempt to destabilize Lebanon.”

Moscow condemned the “resumption of political assassinations” in Lebanon, the Russian foreign ministry said.

The European Union condemned the killing and said those behind the slaying must be brought to justice.
“Those responsible for this cowardly assassination … must be found and judged,” EU Foreign Policy Chief Javier Solana said.

Jordanian King Abdullah II said the murder was a crime aimed at destabilizing Lebanon.
The king denounced what he called a “cowardly crime that is targeting the security and stability of brother Lebanon,” the official Petra news agency said

AND OF COURSE, Sheikh Pierre’s killers denounced as well

Syria
condemned the assassination, calling the shooting of the anti-Damascus politician a “despicable crime aimed at destabilizing” Lebanon.

“This odious crime is aimed at destabilizing Lebanon and disturbing the civil peace in the country,” an official source said, quoted by the state news agency SANA.

The source said Syria worked to ensure “the security of Lebanon, its stability and unity of its people, and to preserve its civil peace“.