Saw this from an oversea site:
"Sharp were and are working on the 904SH before the 903SH got released. Phone companies have a road map, and they start development usually 1 - 2 years before they get released. Japanese companies (NEC, Sharp) like to announce their phones around a month before release, whereas Euro/US companies (Nokia, Motorola, SE, etc.) like to announce their phones 6-9 months before they get released, quite annoyingly." ...
http://www.howardforums.com/archive/topic/734049-1.html