All the mobile carriers started "Emergency Mobile Bulletin Board" right after the quake on 3/11.
Source: WirelessWire News, 3/11
NTT DoCoMo: iMenu top menu, only available to upload from Aomori, Iwate, Miyagi, Akita, Yamagata, Fukushima, Ibaragi, Tochigi, Gunma, Saitama, Chiba, Tokyo, Kanagawa, Niigata, Yamanashi, Nagano prefectures. For smartphones, Emergency Bulletin app is available from DoCoMo Market.
au (KDDI): EZ Web top menu, or auone top menu
Softbank Mobile: Yahoo! Keitai or My Softbank, and iPhone Emergency App
E-mobile: Bookmark -> EMnet service
Wilcom: http://dengon.clubh.ne.jp
For access from PC, see the following:
NTT East (Fixed Local) is providing Emergency Bulletin Board Dial 117 and Broadband Bulletin Web117.
Michi