Last modified: 2010-05-26 10:05:53 UTC
I don't know how you get timezone information for users to choose in user preferences in MediaWiki, but it seems to me that you are using Zoneinfo (http://en.wikipedia.org/wiki/Zoneinfo), right? Anyway, it needs updating, at least for Asia/Saigon. Saigon has officially changed its name to Ho Chi Minh city since 1975, and there is no reason to keep that timezone anymore. You can see discussion about changing it on the Internet, such as, http://thread.gmane.org/gmane.comp.time.tz/2122, and the fact is Zoneinfo has changed timezone Asia/Saigon to Asia/Ho_Chi_Minh since 2008 http://en.wikipedia.org/wiki/List_of_zoneinfo_time_zones. Could you consider updating or changing your timezone database? As you know, most of Vietnamese Wikipedia users are from Vietnam and they will consider Wikipedia very out-of-date in naming timezone. :)
Re-assigning to Wikimedia component. As far as I know the data comes from PHP and MediaWiki just shows what it gets.
Indeed, this comes out of whatever timezone database is available in the PHP package or system. This is being maintained by PHP/Zend and Ubuntu; as updates come in we'll get them. Note that the zoneinfo DB in recent versions of PHP include entries for both Ho_Chi_Minh and Saigon (for compatibility).
Asia/Ho_Chi_Minh is available as an option in the time zone list. Asia/Saigon is kept for backwards compatibility. There's no configuration using Asia/Saigon by default, it's only available as user option.