I'm very aware of DST issues, and even .30 or .45 hour timezones. It is not easy.
Perhaps even just getting the IP of the user, then querying the timezone that way. And if the user is behind a proxy, you can screw yourself anyways
Basically, I am not that concerned with 30 or 45 minute differences (don't have such contacts, but I know others would like that), I'd just want a clock below contact's avatar that would be user settable to predefined time offsets - perhaps not even necessary to input timezone and/or DST - just an option to type in the OFFSET from YOUR system clock time. That would be swell.
And I do know that I can't expect it, like, tomorrow. It's not burning under my feet - I'm a patient man. Would be extremely cool if it were a dedicated Msg+ feature. To whom I need to talk to carry the feature request over?