dez, stop spreading misinformation, it's become a bad habit. Also, stop speaking on behalf of all Pakistanis, you don't have that right.
Imran Khan is not a "supporter" of Taliban, he is, however, sympathetic to their demands and anti-Army offensive, and for this, his popularity recently has suffered. I don't agree with him about the offensive, but he is far from a religious extremist himself. He is also quite popular amongst some of the youth and the educated middle class, and his party had been gaining popularity until recently. That is because he was against the idea of sending the Army into the tribal regions back in 2005, which was and is how most Pakistanis still feel. There are also other reasons for his popularity, he seems to be the only politician who is in touch with the middle-class.
Anyway, there are many reasons why Imran Khan would make a good mediator. However, as Rehman Malik said, talks can only take place if the Taliban lay down their arms. Surrender is the only way forward for them. Once that is done, I have no issues with IK being a mediator.