From Gizmodo:
au is all set to launch their “EZ Book Land!” e-book service in Japan, hoping to breathe new life into the dying market. I seem to recall e-books failing on pretty much all fronts, but given most of us have our mobile phones close at any given moment, this may prove to be a better destination for the contents. au is throwing a wacky business model at the service, where they hope downloading e-books will lead to purchases of the same books on their online store. But you can get comics, leading me to believe this service will be far more successful than previous e-book services in Japan.
Update: I just saw an ad on TV (Animax) for some an AU-related (EZweb) site to read manga.