As I'm sure you're all aware, apparently the man who walked into the CIA compound in Afghanistan and detonated himself was not just anyone. He was a Jordanian intelligence recruit meant to infiltrate Al Qaida, itself.
NBC News Article
According to Western intelligence officials, the perpetrator was Humam Khalil Abu-Mulal al-Balawi, 36, an al-Qaida sympathizer from the town of Zarqa, which is also the hometown of Abu Musab al-Zarqawi, the Jordanian militant Islamist responsible for several devastating attacks in Iraq.
Al-Balawi was arrested by Jordanian intelligence more than a year ago. However, the Jordanians believed that al-Balawi had been successfully reformed and brought over to the American and Jordanian side, setting him up as an agent and sending him off to Afghanistan and Pakistan to infiltrate al-Qaida.
Beyond the tragic deaths of our fellow Americans, what damage was undoubtedly done to intelligence efforts against Al Qaida in Afghanistan/Pakistan in general? Someone reporting back to Al Qaida directly from US and Jordanian intelligence, even though he was at a lower level and would have received very selective information, it is a serious breach - even if all he relayed was training data and infiltration methods in use.