Timezone lookup from latitude longitude [closed]

Answer 1

Timezones are now available via Google API

https://developers.google.com/maps/documentation/timezone/

Answer 2

Eric Muller has made shapefile maps for the timezones of the tz (Olson) database. A few minor caveats, though:

1. The boundaries used are often unofficial.
2. It isn't updated as regularly as the tz database itself, so some newly-formed or -adjusted zones may be missing.

Those aside, however, it seems to be very accurate for most purposes.