Date and time zones?

I asked this a little while ago, but I think I mailed from the wrong
address and it got dropped. Pardon if it’s a dupe.

RT uses (?) GMT internally, but represents things in “local” time.
Local to whom? How is that decision made? It seems to just use time
local to the server. We’ve got users in multiple time zones, and it’s
already caused confusion having people enter “started” times in the
future, for example. Is there any way to have the system use time
relative to the user for display and interpreting input?

I suspect the answer to this is “not without substantial coding”.
Getting time zones right can be tricky. Does the browser send this off
in the http headers? One could also use a new per-user preference,
which is less “nice”, but I imagine much easier.