JMS stated in rec.arts.sf.tv.babylon5.moderated that he’s been asked to address the terrorist attacks within The Amazing Spider-Man by Marvel. Full text is below. In another post, he stated that it would be issue 36.
Here is the relevant JMS post:
Here's where we discover that I have a black transmutational aura that turns whatever weird shit is around me into something substantial. Ever since the events surrounding the WTC, I have said little because, as noted in response to another note, I simply didn't have the words and didn't know where to look for them. And consequently declined invitations to make a statement, on the further grounds that I'm not qualified. Here's where life just nails you. I got an email from Marvel, who felt that in at least one of their books they needed to really address the issue of what happened at the WTC. Their feeling was that the one character best suited to this was Spider-Man because after all, he's a native New Yorker. So they asked me to write it. Unsure if I had the wherewithal necessary to pull it off without embarrassing myself or trivializing the situation through any inadequacies on my part, I asked for 24 hours to think it over. Figured I'd probably pass, since I just didn't know how I could handle it in a comic book format. Somewhere along the way that night, I found the words...and 24 hours after my email, I sent in the script. I think it says what needs to be said. jms (firstname.lastname@example.org) (all message content (c) 2001 by synthetic worlds, ltd., permission to reprint specifically denied to SFX Magazine and don't send me story ideas)