I am assuming that you are asking about a web-based application.
Use of the JavaScript
Date
Object may solve your issue. You can write some JavaScript code that runs on the client PC to compute the local time from the GMT.
var theDate = new Date(2013,01,23,16,15,0,0);
var myLocalDate = theDate.toLocaleString();
Note: I have not tested this solution. I just read my JavaScript manual to learn about the Date object and compose my suggested solution.