The initial code for conversion between Simplified and Traditional Chinese is now in CVS. It uses two conversion tables to perform normal SC->TC and TC->SC conversion. A new wiki tag was introduced to specify special conversions without using the conversion tables, for example, -{zh-cn some_phrase zh-tw some_other_phrase zh-hk yet_some_other_phrase}-. Using -{some_phrase}- along will displae some_phrase for all without any conversion. A quick hack also alows the UI messages to be converted this way, but this is likely to be replaced in the future by a more general way of switching UIs.
Thanks to Tim and Jens at IRC for help!