A good piece on why the Mumbai attacks shouldn't be likened to 9/11. The short version is:
1. It's not apt because this is by no means the first terrorist attack in India, or even the first one this year. This is a country that has a long experience with this sort of thing. The attacking of foreign nationals and the organizational planning of the attack are the only things that make it unique.
2. Likening it to 9/11 pushes the Indian government to respond with overwhelming force, presumably at Pakistan, which is exactly the wrong thing to do, and incredibly dangerous.
I was uncomfortable with the 9/11 analogy almost as soon as I heard it the day the attack happened. This article helps explain why.