Outside of Friends, the only other TV sitcom that was quintessentially New York was Seinfeld.
The city was as much a part of the character as was Wayne Knight, Julia Louis-Dreyfuss or even Jerry himself. However, the show ended in 1998 and never dealt with one of the most tragic events in recent history, specifically September 11th.
There were some shows that dealt with it, specifically The West Wing which based an entire episode on a terrorist attack and its fallout. Friends, on the other hand, decided to bypass the event entirely and not address it.
Anyway, the reason why September 11th and Seinfeld are being mentioned is because a comedy writer has written a script for an episode of Seinfeld that specifically deals with it in exactly the way Seinfeld would have.
The script, which you can read on Google Docs, has the gang bang-smack in the middle of the events. Specifically, it turns out that one of the terrorists borrowed a box-cutter belonging to Kramer. Not only that, George manages to suggest that the firefighters thought it was an 'interesting' week whilst one of Elaine's boyfriends manages to survive the collapse of one of the towers - even though she was planning on dumping him.
Yeah, it goes there. You can read the script in full here, if you fancy.