Juan Cole is one of the most respected Middle East specialists and a highly perceptive critic of U.S. policy and strategy in the Moslem world. In his evaluation of the threat of terrorism today, he makes several important observations.
First,

the original al-Qaeda. Al-Qaeda as a historical, concrete movement centered on Usama Bin Laden and Ayman al-Zawahiri, with the mujahideen who fought in Afghanistan in the 1980s at their core….. That original al-Qaeda has been defeated.
Usamah Bin Laden has not released an original videotape since about four years ago. …I conclude that Bin Laden, if he is alive, is so injured or disfigured that his appearance on videotape would only discourage any followers he has left.
Ayman al-Zawahiri, Bin Laden’s number two man, is alive and vigorous and oppressively talkative. But he has played wolf so many times with no follow-through that he cannot even get airtime on cable news anymore, except at Aljazeera, and even there they excerpt a few minutes from a long tape.
Marc Sageman in his ‘Understanding Terror Networks’ estimates that there are less than a thousand Muslim terrorists who could and would do harm to the United States. That is, the original al-Qaeda was dangerous because it was an international terror organization dedicated to stalking the US and pulling the plug on its economy. It had one big success in that regard, by exploiting a small set of vulnerabilities in airline safety procedures. But after that, getting up a really significant operation has been beyond them so far…

Cole then reviews the major categories of Moslem terrorist organizations that are currently active and evaluates the dangers they pose to the security and safety of the United States. He says:
Terrorist groups are active in four major contexts among Muslims:

1) There are tiny one-off cells (a group of seven acquaintances, e.g., unconnected to any larger organization) among some Muslim communities of Western Europe. They have no real political prospects or import, although they can be briefly disruptive. …These cells are nurtured by the internet and might have dissipated in its absence.
2) There are larger organizations or networks in some Middle Eastern countries that deploy terrorist tactics for political purposes. The radical Muslim movement of Algeria is an example. Al-Qaeda in Saudi Arabia made a push 2003-2006 but was largely repressed.
3) In small territories under what is locally perceived as direct foreign military occupation, organized national liberation movements have sometimes deployed Muslim radicalism as an ideology of resistance and resorted to terrorist tactics, as with Hamas in Gaza, and the Kashmiri and Chechen jihadi groups. …[However] One implication of Sageman’s work is that these groups centered on national liberation seldom pose a terrorist threat to the United States. Hamas, for instance, pledged no attack on the US. Sageman found no Kashmiris among the international terrorist groups– they are focused on their domestic project of liberation.
4) Virtually in a class by themselves are the Islamic State of Iraq in the Sunni Arab areas of Iraq, and the Taliban, whether the Tehrik-i Taliban in the Federally Administered Tribal Areas of Pakistan or the neo-Taliban of southern Afghanistan. …
‘al-Qaeda in Iraq or AQI…. has been attrited in Iraq by Shiite death squads, by American military operations and special death squads, and by the opposition of tribal and other local political forces…The radical Sunnis’ strategy in Iraq, of targetting Shiites and provoking an ethnic civil war, doomed them, since it left them a small minority toward which the majority was deeply hostile. …poor strategy by the Sunni radicals themselves brought the full wrath of Iran, the Iraqi Shiites, Jordanian intelligence, and the United States military down on their heads…
While the Taliban are broadly unpopular in both Pakistan and Afghanistan, they do have some claim on sentiments of sub-nationalism among the Pushtun ethnic group and so have managed to become political movements and not just terrorist groups (though they continue to deploy terrorism as one tool for accomplishing their political goals). …
Although the US is worried about the Arab volunteers who take refuge among the resurgent Taliban, they are a tiny element and cannot easily launch international terrorist operations from FATA. NATO is making a significant error if it does not recognize that the neo-Taliban is more than just a small international terrorist organization. Rather, it has elements of a national liberation organization (in northwest Pakistan it is the lentil-eating Punjabis who are coded as the ‘foreign’ occupiers)…
the Taliban themselves do not pose the threat of international terrorism, though they may give safe harbor to individuals from abroad that do. The focus should be on tracking down and circumscribing the activities of those individuals. Convincing the Pushtun population generally to put up with 70,000 US and NATO troops and with air strikes that kill civilian villagers is a fool’s errand.
Make sure to read Cole’s entire analysis. It presents the reality about the threat of Moslem terrorism today, and not the election year sound-bites about “winning” vs “losing” or “victory” vs. “defeat”