Time Zones for Cities (argh)

[Rich Shockney]

The subject of determining the correct time zone for any city has come up
before in this forum. I am interested in pursuing whether some city -> time
zone mapping might be possible, but wanted to get the opinions of others
here before heading down the wrong path. So, a couple of questions:

  (1) Has anyone successfully done this? I realize that trying to maintain
this mapping manually introduces a technique that will most likely be
error-prone.

  (2) The tz database lists a long/lat for each time zone. If I know the
long/lat for a particular location anywhere in the world, is it possible to
accurately interpolate the time zone given this information in the database?
If so, does anyone know of a good source for long/lat data for major/minor
cities? Is this even possible to achieve? Is there a better way?

And, I'm only interested in current time/time zone mapping and not worried
about historical data, in case that might make the task any easier.

Thanks.
Rich Shockney