This is surely AQ linked. All the hallmarks.
On the contrary I don't think it is, but then we have to be careful about this phrse "AQ linked" or "AQ inspired" that the media is so fond of using. AQ barely exists remember, it's not a top down hierarchical command structure, and it's this that Americans in particular have had serious trouble coming to terms with. It's more of what you might call a central resource (even library if you like) for that reason its near on impossible to strike at its command and control as its something of a network of autonomous inter-related causes, but each with different local grievances. The network itself is something of a learning mechanism that assists, supports and encourages its members or associates to engage. This support can be spiritual, rhetorical, technical, or logistical. As such its a very powerful mechanism as its tantamount to laying out a spider web across the globe and local cells can flash up anywhere. At a stroke it removes the conventional western military doctrine of invading and garrisoning a territory in order to establish superiority.
Not surprisngly the Indians are blaming the Pakistanis and where as I have no insight on this, I am aware that this is normally code for something specific and unique to an organisation within that country, though not AQ as such.
I also note that they used fast boats to launch the attack. This is something I've long wondered about in terms of the UK. We've expended a lot of time and money on shoring up land based defences against a rapid attack, but it strikes me we've left two very obvious high profile levels of weakness that would involve water borne attacks open.
The other thing I note is a mistake that they might have made in 9/11 which this attack has merely sought to demonstrate to me could have been done. Had they palced 20 or so gunmen on the streets of DC in the immediate aftermath they could have taken out hundreds of people as well as some moderately important ones. As the State Department, Pentagon, White House and Capitol were evacuated thousands of workers spewed out on the street in a state of confusion, (many wearing ID cards round their necks). Now wear as any gun battle would have been quickly resolved in the Americans favour due to the high military presence in the areas concerned, the 15 minutes it would have taken would have provided ample opportunity to take down a couple of hundred, especially if they were firing from a mixture of street level close range, and prepared concealed positions. If they were really clever, they might even have been able to set up a controlled panic that ensured people who were fired on from one point, ran back into other escapees who were in turn funnelled into another killing zone.