The Beijing Youth Daily reports:
“Because of SARS, ‘Civet Cat’ (guozili) was registered as a trade mark. Because of an online novel, ‘muzimei’ was registered as a trademark. It seems that ‘pirate registration’ (qiangzhu) is becoming a trend. In the last few days, reporters discovered that someone has applied to register the name of current American president Bush.”
That someone is a Mr Guo from Henan Province. Why use ‘Bush’ for a diaper brand? Because the Chinese for Bush is pronounced ‘bu shi’ which sounds the same as ‘not wet’. Here is a scan of the Beijng Youth Daily article, with an image showing Mr Guo holding up his registration application. The two characters inside the box are ‘bu shi’.

Chinanews.com has reproduced the article here. Thanks to Shanghai Eye for the link.
UPDATE: There is an English article about Bush brand diapers on Eastday.com. Link via Brainysmurf