Why is Yahoo BB able to offer 8Mbps?

[Kyle Wright <webmaster@example.com>]

I have tried looking for information as to why Yahoo!'s BB service
claims that the max bandwidth of its ADSL service will be 8Mbps as
opposed to all the other ADSL providers only offering a max bandwidth
of 1.5Mbps.  However, I have yet to find an explanation as to why
Yahoo! can do this.  Does Yahoo! have some secret formula or do they
just plan on opening the bandwidth tap wider than the others or are
they just putting up fancy numbers (like their deceptive price tag or
990 yen/month @ http://bb.yahoo.co.jp/ )?  What concerns me is that
Yahoo! says they they will be using a best-effort ADSL (
http://bbpromo.yahoo.co.jp/promotion/m_5/index.html#52 ).  Should I be
concerned about this, that is, should I go ahead and get NTT's FLETs
ADSL or should I wait for Yahoo!'s ADSL?

-- 
Kyle Wright, Japanese-to-English Freelance Translator
http://kylewright.com/eiyaku/  mailto:eiyaku@example.com
inuyama.aichi.japan  tel/fax 0568.61.8566