The timestamps on comments will always display in the timezone of the LiveJournal servers, which is US Pacific Standard Time (-800 GMT) or, when applicable, US Pacific Daylight Time (-700 GMT). The times on comments are automatically assigned when they are posted; there is no way to set or edit the time on a comment.
When viewing comments anywhere on LiveJournal, you will need to take into account this time difference in order to compute the local time at which the comment was posted.
Instead of quibbling over where the best place for this is, we will be adding a new FAQ. Please make suggestions and comments for improvement.