The US was moving towards open conflict with Syria recently, especially as US special forces engaged across the border in fighting Islamic militants fighting along the Iraqi border (see Bill Roggio posts regarding here and here). However, Secretary Rice argued against taking military action against Syria in an October 1st principals meeting, according to Newsweek.
In light of the recently released UN Investigative report on the assassination of Lebanese Prime Minister Rafiq Hariri by German investigator prosecutor Detlev Mehlis that directly implicates several high ranking members of the Syrian government and the Assad family, Rice's decision appears to be the right one. For a detailed analysis of the UN report, review Publius Pundit's post by Robert Mayer and this Washington Post article.
Secretary Rice's ability to delay military action against Syria (she has publicly stated the US will not rule out an attack on Syria) has created a opportunity for Europe and the Middle East to be united behind a condemnation of Syria. Even Saudi Arabia and Egypt are likely to put further pressure on Damascus, according to this Arab News article. The report is so detailed and implicating of Syrian involvement that Syria is in no position to step out of line over Iraq.
The added benefit of going the diplomatic route is putting France and the United States, along with the United Kingdom, firmly in the same camp over condemning Syria and taking strong action (see WaPo article). This move will likely help go towards repairing the Atlantic alliance.