One Segu has started in Japan on April 1, as promised (see my earlier post from September 2005):

NHK and five commercial TV broadcasters held a splashy launch party in Tokyo's central Shinjuku train station on Saturday afternoon, announcing the official start of terrestrial 'One-Seg' broadcast services. The carriers have lined up accordingly: NTT DoCoMo has partnered with Nippon Television and Fuji Television, while KDDI has forged a partnership with TV Asahi.

via Wirelesswatch.jp

Here you can see a several minutes demo of mobile "One Segu" TV . The quality of the picture on the handset is amazing and I think if we get the same quality and pricing here, this will be a different game. Right now we are just too far behind Japan.