Isn't it already so?
doesn't vroom, or perlmonks, store timestamps in gmt format, and then converts to whatever timezone yet settings are, be you you, or AnonymousMonk?

update:
Pardon my Ignorance, i'm glad I caught this immediately.
I don't like this idea.
Someone also suggested a feature like this a while back, so people'd know when stuff was posted via [time something] format.
I don't like it cause it's kind of useless. What does please resond to this by this time mean to anyone. The site is here as a resource for all people at all times, at the leisure of the monks who contribute. Nobody is on any kind of timelimit to respond, and shouldn't feel so. Postsers should be patient.

One of the worst nodes of all time used to be by some lazy who was taking a perl class, and came in yelling for help on his final. He told his teacher he needed to go to the bathroom, got on a computer, and whined for someone to give him the answers so he can cheat.

That is comes to mind when i see "Please respond to this by [Time ricockulous], and that kind of pisses me off.

In conclusion, I see very little usefulness in such a feature, and am therefore, against it.

 
___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"