A stabbing spree occurred in Akihabara yesterday. Patrick has some links with more detail.
I wonder how much affect this will have on Akihabara. True, it can't be good, but Japan seems to be experiencing a wave of stabbing incidents like this lately and I'm not sure how much they've hurt the areas they happen in. There's also been a substantial amount of petty crimes targeted at otaku who are known to not defend themselves, so it's not as if Akihabara was completely safe. I won't deny that this is bad, but I wonder if it can do as much damage to Akiba as Tsutomu Miyazaki did to otaku; I suppose it remains to be seen.
There might be a greater impact on foreign visitors to Akiba. Japan is usually pretty safe, but this leads to a common misconception by foreigners that things like this never happen, that Japanese people are somehow superiorly well-adjusted and don't have these sorts of issues, and recent incidents like this pretty blatantly prove that false. My understanding is that within Japan they're happy to promote this idea as well. Japan has no social problems, and heaven forbid anyone actually admit to mental problems within their family or group of friends and then do something like get them help (so things just simmer untended until they boil over into hikkikomori, or suicide, or this). General anti-American and anti-gun sentiment plays into this too--clearly only Americans with our/their failed culture and easy access to guns would be so horrible.
I don't know. I hope Patrick's wrong, that this guy didn't just kill Akiba. But if he is an otaku (I can't quite tell from the reports, it seems like he's not, just a guy with issues), or if the media decides it's convenient...