Converted unicode numbers (in category name, entry title and comment author) to unicode string. The bug of duplicate categories in WP 2.3 was solved by this.
For a Chinese characer “游”, its unicode number is 28216. It might be represented in HTML as “游”, the browser is able to recognize and convert it. It’s unicode codes are 6e38, in python, represented as a unicode char u’\u6e38′. To convert a unicode number to unicode char, in python, use the function “unichr”.