There was an interesting passage in the Alistair Campbell diaries, pre 9-11, where they asked Musharraf about the Taleban leaders in next door Afghanistan.
"Can we talk to them?" He asked.
"There is no point," he said. "He talks completely in the context of the afterlife."
I think traditional diplomacy has long since failed.
In fairness, the easiest political thing for Brown to do is play the strong-leader 'i'll never talk to them' card.
But one thing that the aftermath of Iraq has shown is that excluding those who used to be in power completely is simply not sensible, no matter how unpalatable that option appears to be.
"the Taleban" is a disparate group and there will of course be sections more inclined actually to pursue peace rather than power.