This was a very well coordinated, highly advanced attack that took months to prepare and train for. Given that fact, and the fact that the terrorists were apparently all in their late teens and early 20s, very young, that tells me there had to be some larger force involved to help them plan and pull this off (Al Qaeda, the Pakistani ISI, or perhaps even both, considering the ISI's rogue tendencies and anti-Indian Islamist ties).
The perps were likely members of one or more Kashmiri, Pakistani or homegrown Indian Islamist groups (smart money is on Lashkar e-Taiba, with Al-Qaeda oversight).
Targeting Westerners and Jews is par for the course for Islamic terrorists--but what were these guys looking to accomplish overall? Was this to draw attention to the Kashmir issue? To drive a renewed wedge between India and Pakistan, whose frosty, volatile relationship has thawed a bit in recent years? Or just a general statement of strength from Al Qaeda, which has taken plenty of lumps as of late (see Iraq, drone missile strikes in Pakistan)?
The techniques here were new for Islamist terrorists--hostage taking, with no apparent demands, and no suicide bombers (at least not at the outset of the operation). Considering all of these facts, the larger, more pressing question is--could AQ or its surrogates pull this kind of attack off in the U.S. (enter an American port city via boat and go after soft targets)? A scary thought.
Al Qaeda has always wanted to top 9/11 with its next attack on U.S soil. They have not been able to do that for a variety of reasons, so I look for them to lower the bar a bit here and perhaps 'settle' for smaller yet still deadly and chaotic plots like subway attacks. The recent NYC terror warning reflects that, I think.
A closing thought--at least two of the terrorists were apparently British citizens. Britian's radical Muslim population--many of whom make trips to Waziristan for training--has become, in recent years, a serious problem on a global scale.