The Taliban want an end to the drone attacks. The Pakistan Air Force has the capacity to do so but the armed forces realize the repercussions of downing the CIA drones. This is thus one key demand that cannot be met. They then want all their prisoners to be released. The government for some reason has already started the process without even the start of parleys and without securing anything in return. In fact, the Taliban also are holding on to many kidnapped personnel, including an American soldier and an American contractor kidnapped from Lahore, and a few other European nationals. The Taliban prisoners could have been released in return for at least these abductees but this was not done.
Taliban profess to stand for complete Islamization of the society. It is a different matter that their actions hardly conform to any morality. Nevertheless, this is their major political demand and any negotiations with them may result in intense pressure to adopt Shariah. The governments in Islamabad are in the habit of yielding to such religious pressure since the inception of the country but it is leading to more and more fissures in the national polity.