The Raw Story reports that the United States and its coaltion allies do not classify the organization as a terrorist group. According to State Department documents, the Taliban has not been classified as terrorist for the past six years. The Taliban provided safe haven for Osame bin Laden and al Qaeda, and is currently in southern Afghanistan, intimidating villagers and ambushing vehicles.
No reason is given for the omission of the Taliban as a terrorist organization. State department officials describe the group as "an insurgent organization that will periodically use terrorism to carry out its operations." Using George W. Bush's definition, this would make the Taliban terrorists.
Though it may not be relevant, it is worth nothing that since the mid-90's, the United States has negotiated on and off with the Taliban for various oil pipeline deals; one such negotiation was taking place as late as 2001.