"If you have set your local time zone, the time stamp displayed on a comment that is viewed on a site scheme comment page or on certain customized comment pages will be in that time zone. These time stamps will generally have text indicating that they are displayed in your local time zone, such as "(local)".
Most S2 styles do not currently have timezone support for the time stamps that are displayed with comments on customized comment pages. Until this functionality is added to all system styles, some styles will not display time stamps in your local time on your comment pages.
If you have not yet set your local time zone, or if the style you are using does not yet have time zone support for customized comment pages, these time stamps will display in UTC (Coordinated Universal Time), which is also known as GMT (Greenwich Mean Time). The labels "UTC" or "GMT" may or may not accompany these time stamps."