Al Qaeda made a comeback in Saudi Arabia, with a February 24th suicide car bomb attack on the largest oil production facility in the country. The two cars were stopped by security guards (leaving three of the guards dead) and gunfire. The two bombs went off, killing the terrorists. Al Qaeda took responsibility for the attacks, and DNA tests of the bombers found that they were on the "36 Most Wanted Terrorists" list the Saudis issued last year.
Al Qaeda, in effect, boasted of this failure because, despite much effort, and rhetoric, al Qaeda has been unable to do much in Saudi Arabia over the past year. This is particularly embarrassing, as Saudi Arabia is the home of al Qaeda, and source of its most generous financial benefactors. The Saudis have been trying to shut al Qaeda down at its source, but it has been difficult. This is because al Qaeda has tied itself so closely to the Wahhabi sect of Islam, which is the most popular sect in Saudi Arabia (and was founded there in the 18th century). Al Qaeda, and its supporters, survive in Saudi Arabia, but this failed attack will hurt the terrorist movement. Saudis know that the oil is the only thing standing between most of them and poverty.
On February 26th, police arrested twelve al Qaeda suspects on a farm. Two of the men were injured when they tried to escape. On February 27th, police caught another six al Qaeda terrorists, who had helped the two bombers involved in the February 24th attack. Five of these men were killed in the shoot-out, and one was captured.
The February 24th attack was worrisome, as the attackers managed to get through one layer of checkpoints, but were stopped by the second (which was still two kilometers from the main gate of the complex). The Saudis have long put a lot of effort into the security of their oil facilities, and the aftermath of this attack will probably make those facilities more secure.
For the last three years, the Saudis have been at war with al Qaeda. Before that, the terrorists were largely tolerated in the kingdom, as long as they stayed quiet and out of sight. But after the U.S. invaded Iraq, al Qaeda became active in Saudi Arabia. It was forced to, as al Qaeda always maintained that it's primary mission was to keep infidel (non-Moslem) troops out of Arabia. American troops in Iraq could not be ignored, but terror attacks against Saudi targets destroyed much of the support al Qaeda had long enjoyed inside the kingdom.
Saudi security forces have tried to infiltrate and monitor al Qaeda cells in Saudi Arabia, in order to get a warning of any serious attacks. It's not known if the Saudi intelligence people knew, beforehand, of the February 24th attack. But the speed with which they arrested other al Qaeda members indicated that the government knew a lot about who was who, and where they were.
Al Qaeda has announced that they will make more attacks, but first they will probably try to shed police informers in there midst. This is likely to get messy, as these "cleaning" operations often take down some loyal members as well.