Yoshito,
I'm maintaining a mapping data between the IANA tzids and Windows time zones in the Unicode CLDR project and review the data about quarterly basis [ http://www.unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml ].
I'd say you're doing an awesome work! Do you think I could use your work to improve libical regarding to timezone information? We are using libical in Evolution (and its friends) and, in evolution-ews, would be nice if we can have this mapping working properly. Another question is ... do you think cldr could replace libical? This is the first time I heard about the project ...
It looks Windows 8.1 start providing an API returning an IANA Time Zone Database ID [ http://msdn.microsoft.com/en-us/library/windows/apps/windows.globalization.c...], but I did not try it yet.
I am not able to open this link, unfortunately. ps: Yoshito, please, remember me to pay you a beer whenever we meet in person! Best Regards, -- Fabiano Fidêncio