We initially went to war to destroy them and take out Osama bin Laden. However, that just war got put on the back burner so that we could pursue some other grand End to Evil strategy that had basically nothing to do with September 11 and our inital causus belli. The Taliban is therefore still around, as is Osama bin Laden, who is, we are assured, no longer relevant.
Short of a major and preemptive military invasion into Pakistan, both are likely to remain with us for at least the immediate. I would also urge conservatives not to pooh-pooh Obama's actual proposal on this too much since it may well come to that. However, anyone who has been even remotely following the discussion on Iraq would be aware that regardless of why Mark believes we went to war, we are actively fighting Osama's jackboots there as well. Allowing the enemy to regroup, whether in Pakistan or in Iraq, would be a Very Bad Thing.