I am extremely sorry to expose my ignorance.
The Americans have recently started devoting greater resources to the hunt for the man on the top of their most wanted list. George Bush, it seems, wants the man he vowed to capture "dead or alive" before he leaves office. There have also been reports of Bin Laden at various points in Pakistan's border region, some of them placing him in north Waziristan where the "Pakistani Taliban" is the de facto ruler after a series of deals with the government in Islamabad. There have also been reports that the US came close to killing Ayman al-Zawahiri, deputy leader of al-Qa'ida, in air strikes.
But US and British commanders privately admit they are seriously hampered by a lack of intelligence about the whereabouts of the al-Qa'ida leadership. They cannot depend on the ISI, the Pakistani secret service, which is widely perceived to back Islamist terrorists
In July 2006, the CIA unit tasked with hunting Bin Laden, codenamed Alec Station, was closed. Iraq was still the main focus of Washington's attention and it was felt resources were needed there.
The task of finding Bin Laden, said a senior security official, is now more difficult than ever. "Since the elections in Pakistan we have got to be more careful about carrying out air raids across the border, although if we have a sniff of locating Bin Laden there'll be no compunction about ordering a strike, but I wouldn't bet on when that will be."
http://www.independent.co.uk/opinion/commentators/kim-sengupta-why-bushs-dead-or-alive-posse-havent-got-their-man-887128.html