GMT offset zones reversed
The GMT timezones in the TZ database are opposite of what they appear they should be. i.e. GMT-4 is really GMT +4.
This is "by design": http://www.freebsd.org/cgi/query-pr.cgi?pr=24385
but should be accommodated in some fashion since it's very confusing. Probably remove from web interface entirely.
(moved from cvstrac)