So far in 2006, suicide bomber attacks in Iraq are down fifty percent, as is the use of IEDs. The reduction in suicide bomber attacks is largely due to the reduction in the number foreign terrorists getting into the country. This is the result of several factors. First, there are fewer foreigners trying to get it. The rest of the Arab world has found out about how unpopular Islamic terrorists are inside Iraq. It's hard to justify "dying for the Iraqi people," if the Iraqi people really want you to go kill yourself somewhere else. Then there is border security, which is a lot tighter. The towns on the Syrian border, which used to be controlled by terrorist groups, are now either controlled by the government, or being contested by American or Iraqi troops. In either case, the Islamic terrorists can no longer use these towns as way stations for the trip to Baghdad. In addition, the Iraqi border guards are more numerous and in control of more of the border. The border guards of neighboring countries are also more cooperative, either blocking Islamic terrorists, or not assisting them. Going cross country to cross the border is less of an option, with more American UAVs in action to spot people moving about where they shouldn't be.
Another major factor in the reduction in bomb attacks, can be attributed to the tactic of looking for the bomb makers, and killing of capturing them. Last year, 115 bomb makers were put out of action that way. In the first three months of this year, another 25 bomb makers have been taken down. Along with this, dozens of other bombing specialists have been nailed. These include the financiers (usually former officials in the Saddam government) and team leaders (for scouting and selecting bomb locations, placing the bombs, and detonating the bombs and carrying out any accompanying ambush.)
There are still thousands of potential bomb makers out there, primarily former members of Saddam's special forces and military engineers. Most of these guys have stayed away, noting how dangerous a job it is, and are currently more willing to make peace with the new government. The Sunni Arab community uses these potential bomb makers as a bargaining chip with the government. If the Sunni Arabs don't get a deal they can live with, including government jobs and a cut of the oil money, they will keep building bombs. A lot of the bombing that is still going on is more a bargaining ploy, than any serious attempt to put a Sunni Arab dictator back in charge of the country.