Well the Pakisthan is doing something for sure, but it is not to co-operate with India but rather US has leaned too much on Pak to do that. Coz, US realises that mumbai attack has been drawn parallel with 9/11 and India might consider military option just like US did. Now US does not want this to happen as that will make pak move their troops from western border to eastern border and US does not have the manpower. If the arrested men are handed over to India or US then it would make sense. What ever pak did was in the vested interest of US. Pak Gov is doing what US wants pak to do which was the reason for Musharraf's downfall. Also with Obama with his idea to strengthen the afgan border and pursue attack in Pak which is something Pak does not like and has not allowed US to do, This mumbai incident gives US the ammo to go after Pakisthan gov by threatening to list Pak as state sponsor of terror and negotiate more from Pak and make India happy or neutralize the reason for military attack by going after those Guys who will probably enjoy more protection from possible Indian missile attack. It's a political game of chess.... :)