Saudi Arabia, which normally makes its influence felt behind the scenes, has been unusually assertive of late, as I wrote a few weeks ago. It brokered a deal between Fatah and Hamas in Palestine, called Iran's Ahmadinejad over for a dressing-down, hosted the Arab League summit, and just recently branded the U.S. "occupation" in Iraq "illegal."
Here's a reasonably good discussion of Saudi Arabia's recent moves by Rachel Bronson of the Chicago Coouncil on Global Affairs, author of "Thicker than Oil: America's Uneasy Partnership with Saudi Arabia." She notes that part of the explanation is that "With the United States regionally hamstrung and President Bush domestically neutered, [King] Abdullah has clearly decided to take matters into his own hands."
I think that puts it too kindly. I suspect Saudi Arabia has watched Dubya (ironically the son of one of Saudi Arabia's best American friends) blunder in Iraq and elsewhere and decided that as long as he is president the Americans are going to be hopeless -- flailing like an overgrown baby in a room full of delicate crystal, spreading instability and resentment wherever they go in the Middle East. The Saudis' other concern, of course, is Iran, which it has been watching guardedly for 30 years. The Saudis really don't want Iran to get nuclear weapons and become the clearly dominant power in the region, and the American intervention (which gave Iran influence in Iraq that it could only dream of before) and posturing is making such an eventuality all the more likely.