Over at Stategy Page, there's an essay describing the how as Iraqi secutiry forces take over more of the daily policing activity, more American forces are free to go on the offensive aginst terrorists, especially as they cross into Iraq from Syria.
Over the weekend, intelligence efforts discovered five terrorist safe houses, which resulted in attacks by smart bombs and ground troops. At least twenty terrorists were killed, and large quantities of weapons, bomb making materials and documents were captured. The documents, and interrogations of captured suspects leads to more information on where the terrorists have there safe houses, weapons caches, and travel routes across the Syrian border (the main source of suicide bombers, who are almost all foreigners, and cash.)
Most of these foreigners either get killed as suicide bombers, or stay for a while, then go home. Those who go home are often disillusioned with their experience in Iraq, as they see up close how most of the victims of al Qaeda violence are Iraqi civilians. The really hard core foreigners die as suicide bombers, or in other fighting with American or Iraqi forces. The ones that leave Iraq, often do so out of frustration. These foreign volunteers came to fight the "American occupiers," but are quickly made to realize that going after the Americans is suicidal, especially for largely untrained (in military matters) foreigners (who reveal themselves as foreigners as soon as they speak, using a foreign dialect of Arabic.)